Pneumatic Sifter
The Sifter separates loose materials with blasted air, tumbling, and optional fluid solvents. Sifted materials have a chance of producing more refined loose materials as well as ore nuggets. Early game resource manipulation with micro-multiplication. Uses late-game resources for better effect.
Input:

• Dirt / Gravel / Sand
  Output:
• Gravel / Sand / Ore Nugget / Flint / Bone / Seed / Clay
  Upgrades:
• Magnet (ore chance) / Life (looping) / Security / Speed / Volume
• Water = increases output chance
• Lubricant = greatly increases output chance
• Vegetable Oil = increases output chance; with dirt input, clay output; with sand input, dirt output
• Advanced = produces heat; too high heat causes organics production (dirt/clay) to fail?
  Consumes:
• Pressure / Air
• Compressed Iron Bars = sifting grate?
• Chance bonus with added fluid? (Water/Lubricant?)

Pneumatic Mill
The Mill pulverizes Stone / Cobble / Ores / Wood. Mid-game resource manipulation, providing an alternate path for acquiring harder to acquire resources. Room for upgrading to late-game efficiency.
Input:

• Ores / Stone / Cobble / Wood
  Output:
• Milled Ores / Cobblestone / Gravel / Sand / Planks / Sticks / Dust / Heat
  Upgrades:
• Standard Upgrades
• Mill Blades/Drills?
• Mill Blade type (stone/iron/diamond/etc) required for mining level of ore; affects consumption rate
  Consumes:
• Pressure (and Sand?)
• Mill Blades

Thermopneumatic Forge
Brings effective smelting to Pneumaticraft! Also reliable ore doubling using materials produced by the P. Mill (Milled Ores). Possibility for RNG with additives for late-game efficiency? Also possible integration with plastic resource for Plastic Injection Moulds - perhaps creating plastic buckets / boxes, etc.
Input:

• Ore / Milled Ore / Smeltable resources / plastic injection mould + molten plastic
  Output:
• Ingot / 2x Ingot / smelted resources / plastic items / etc
  Consumes:
• Pressure
• Heat

New Dependant Resources / Items
New resources produced by the above machines that allow for regulating doubling to keep it balanced.
Milled Ores (thematic alternative equivalent of dusts)

• Ores cracked in a TP Mill, basic ore doubling
• Can be treated by different machines for 2x-4x chance, depending on additives and consumable components?
  Dust
• OreDict:Dust?
  Sifter Grates
• Wood - Netherite, consumeable, impacting processing chance of machine for secondary outputs
  Mill Blades
• Stone through Netherite, consumeable, impacting processing time, limiting the processing of higher tier ores by blade quality
• Could even just use "gears" according to OreDict
  Misc. Note:
  ***Advanced/T2+ blades/drills/components could require Assembly Station for manufacturing

I have taken the liberty of creating another kooky flowchart describing a modified variant of the ore multiplication process I devised in an earlier comment. Take a look at it here: https://tinyurl.com/smtna4yb

This process deviates from my original idea quite a bit. Here are the differences:

• I separated the fluids and sheets into distinct types, following desht's feedback
• I adjusted the required temperatures for each step, trying to keep true to the melting point of things in real life (though, some backing-off real life's rules was needed in some areas)
• I enforced a Pressure requirement for the first step.
• I fixed the Heat Frame Cooling numbers, following desht's advice. Hopefully I got the numbers right this time. Some adjustments to bonuses was needed in other steps to account for this change.
• I got rid of the idea regarding infinite resource production by converting Cobblestone into Slurry, as it was too unbalanced.
• I changed the process for renewable sand/gravel by introducing a new fluid called Sediment, which needs some initial Slurry to acquire. Once you have some, you can freely convert any piece of Cobblestone, Diorite, Andesite or Granite into either Gravel or Sand using the TPP.
• Following desht's feedback, I changed the requirement for Diesel/Biodiesel to instead require Lubricant, in a much smaller quantity (25mb)
• Perhaps the biggest change: I switched the Pellet production process from using the Etching Chamber / UV Lightbox to using the Assembly Platform. The reason for this is mostly because the current implementation of the EC/UV combo is too closely tied to PCB production, but also because 1) I wanted to gate 5x ore multiplying behind PCBs and 2) The EC/UV combo was incredibly complex, considering the necessity for Etching Acid. Instead of exponentially increasing the machine automation complexity. this change exponentially increases the production rate. This is in a way more balanced. as the player is making a very harsh tradeoff in production speed for resource efficiency.

I was playing through the mod and a thought occurred to me - some of the machines seem like they are only made for one purpose and I felt like it would be neat to be able to do more with them.

I then remembered you were considering an ore multiplication system, so I challenged myself to design one by using only the machines and mechanics that are already present in the mod. It seems a little random in some areas, but I thought it was cool regardless. This is fleshed out up to 5x ore processing, involving a little randomness and a lot of complexity involving pressure, cooling, heating, acid, etc, starting at 2x.

The only mechanic it doesn't really touch is the Assembly Table. I did try really hard to think of a way to include it in an ore processing setup, but it just didn't fit thematically in my head.

I figured that you may find some of these ideas interesting.

New Items/Fluids:

• Slurry: A liquid which is a byproduct of the first tier of ore processing, but also a required reagent in the second tier. It can also be processed into Gravel and Sand, which are now made renewable.
• Molten Metal: A liquid representing an ore/metal in it’s fluid form. Unlike other mods, which add multiple different kinds of metallic liquids, this is just one liquid. The liquid contains data as fluid tags, representing which ores/metals it contains and what quality the metal is. For example, a Molten Metal fluid may have one of the tags “Impure”, “Pure” or “Pristine”, representing it’s quality. It may also have any number of ore tags, like Iron, Gold, or Copper. If the tag representing quality is “Impure”, then that means this fluid has multiple minerals in it (much like how rocks work in real life), and a percentage number will represent how much of the fluid contains what amount of a particular metal. Think of it as a fluid version of a Spawner Core, except for ores instead of mobs. Here are some possible variations:
  • Molten Metal (Impure 50% Iron 50% Gold)
  • Molten Metal (Impure 75% Iron 20% Copper 5% Gold)
  • Molten Metal (Pure Iron)
  • Molten Metal (Pristine Gold)
• Metal Sheet: Like it’s plastic counterpart, this is the hardened form of Molten Metal. It can be made by cooling Molten Metal in the same way plastic is cooled, with bonuses for temperature efficiency. Unlike other mods, which add separate ore dust/chunk items, this is just one item. The distinct metal is indicated by an item tag, so you can have Metal Sheet (Iron) or Metal Sheet (Gold), etc. When Impure Molten Metal is cooled into Metal Sheet, it picks the most dominant metal in the fluid and becomes that metal, losing the other metal content. Like so:
  • Molten Metal (Impure 75% Iron 25% Gold) -> Metal Sheet (Iron)
  • Molten Metal (Impure 25% Iron 75% Gold) -> Metal Sheet (Gold)
  • In the case of an equal balance, like (Impure 50% Iron 50% Gold), it will pick one at random.
• Metal Pellet: This is both an intermediary crafting component and a reference to how real-life pneumatic ore processing facilities work, where they produce pellets of metal. It is made by compressing Metal Sheets in the Pressure Chamber, bathing them in acid in the Etching Tank and then drying them in the UV Lightbox. It too, contains tags representing it’s stage and it’s mineral/metal. Here are some examples of tags:
  • Metal Pellet (Rough Iron)
  • Metal Pellet (Varnished Gold)
  • Metal Pellet (Polished Gold)

The 2x-5x Multiplication Process:

1. First tier (2x): Washing the Ore in the Thermo-Pneumatic Processing Plant.
   1. Inputs: 1x Iron Ore, 1000mb Water
   2. Outputs: 18x Iron Nugget, 1000mb Slurry
   3. Required Temperature: Between -20c to 0c
2. Second tier (3x): Converting an Ingot and Slurry into Molten Metal (Impure) in the Thermo-Pneumatic Processing Plant, then converting Molten Metal (Impure) into Metal Sheet using Heat Frame Cooling, then smelting Metal Sheet into Ingot in a Blast Furnace.
   1. Inputs: 1x Iron Ingot, 1000mb Slurry
   2. Outputs: 1000mb Molten Metal (Impure, 75% Iron 15% Gold)
   3. Required Temperature: >= 300c
   4. Cool 1000mb Molten Metal (Impure, 75% Iron, 15% Gold) into Metal Sheet (Iron) using the same mechanics as Plastic. Heat Frame cooling has a 50% chance to output 2x Metal Sheet (Iron) if cold enough (< -100c). If not, it will only output 1x.
   5. Smelt Metal Sheet (Iron) into Iron Ingot in a Blast Furnace (regular furnace doesn’t work).
3. Third tier (4x, with bonus metals): Refine and purify mixed Molten Metal (Impure) into multiple separate Molten Metal (Pure) inside the Refinery. Then, use Heat Frame Cooling to turn Molten Metal (Pure) into Metal Sheet. Then, smelt Metal Sheet into Ingot in the Blast Furnace.
   1. Inputs: 1000mb Molten Metal (Impure, 75% Iron, 15% Gold)
   2. Outputs: 750mb Molten Metal (Pure Iron), 150mb Molten Metal (Pure Gold)
   3. Required temperature: >= 1000c
   4. Cool Molten Metal (Pure Iron) with a Heat Frame. -300c is required to turn 1000mb Molten Metal (Pure Iron) into Metal Sheet (Iron), with a 50% chance for 3x the output, which will only work on “Pure” molten metal. “Impure” molten metal is limited to 2x.
   5. Smelt Metal Sheet (Iron) into Iron Ingot in the Blast Furnace.
4. Fourth tier (5x): Compress Metal Sheet into Metal Pellet (Rough) in the Pressure Chamber. Then, smooth out the rough surface of the Metal Pellet (Rough) by giving it an Acid Bath in the Etching Tank to turn it into a Metal Pellet (Varnished). Then, “dry” the Metal Pellet (Varnished) in a UV Lightbox to turn it into a Metal Pellet (Polished). Then, turn the Metal Pellet (Polished) into Molten Metal (Pristine) in the Thermo-Pneumatic Processing Plant. Then, use Heat Frame Cooling to turn the Molten Metal (Pristine) into Metal Sheet. Then, smelt the Metal Sheet into Ingot in a Blast Furnace.
   1. Input 2x Metal Sheet (Iron) into the Pressure Chamber to get 1x Metal Pellet (Rough Iron). This requires 5 bar of pressure and will consume a lot of air. You will likely need to supply air to the Pressure Chamber through multiple valves in order for it to keep up with a large batch.
   2. Insert Metal Pellet (Rough Iron) and Etching Acid into an Etching Tank to get Metal Pellet (Varnished Iron). This requires a temperature of >= 100c. The Etching Acid will be consumed. It follows the same mechanics as the Printed Circuit Boards, except that there is a temperature requirement.
   3. Insert the Metal Pellet (Varnished Iron) into a UV Lightbox to get a Metal Pellet (Polished Iron). It follows the same mechanics as the Printed Circuit Boards, except that there is no chance of failure.
   4. Insert the Metal Pellet (Polished Iron) and 1000mb of Diesel/Biodiesel into the Thermo-Pneumatic Processing Plant to get 1000mb of Molten Metal (Pristine Iron). This requires a temperature of 1500c.
   5. Cool Molten Metal (Pristine Iron) with a Heat Frame. -500c is required to turn 1000mb Molten Metal (Pristine Iron) into Metal Sheet (Iron) with a 50% chance for 4x the output. 4x will only work on “Pristine” molten metal. “Impure” and “Pure” molten metal are limited to 1-3x.
   6. Smelt Metal Sheet (Iron) into Iron Ingot.

Additional New Recipes/Mechanics:

• 0.5mb of Water + 1 Cobblestone (or Granite, Andesite or Diorite) in the Thermo-Pneumatic Processing Plant = 0.5mb of Slurry (between -20c and 0c)
• Slurry can be converted into Gravel or Sand in the Thermo-Pneumatic Processing Plant. 100mb of Slurry will turn into 1 Gravel when between 300-600C, and 100mb of Slurry will turn into 1 Sand when above 600C.
• Two or more different types of Pure or Pristine Molten Metal can be re-combined into Impure Molten Metal in the Fluid Mixer. This acts as a way to “compress” all the different kinds of ore fluids into a singular fluid for easier storage, especially in a big modpack environment with lots of custom ores and metal types.

Questions/Answers:

Question: Why use Iron Ingots in the tier 2 phase? Doesn’t this create an infinite resource loop?
Answer: This is why Slurry is required as an input for this tier. The only way to get Slurry is by breaking down ores or converting a LOT of cobblestone, which acts as a way to prevent cheesing the process, so you can’t just magically double ingots infinitely. You’d run out of Slurry eventually.

Question: So, technically one can just generate resources from thin air with a cobblestone generator as long as they already have an ingot to start with?
Answer: Yes, but it'd take 2000 cobblestone just to get one bucket of Slurry, and one bucket of Slurry is less than 1 ingot of metal. So, it's a huge cobblestone sink, but worth it if you have the cobblestone on hand. Remember that this requires a temperature balance and pressure in addition to the cobblestone.

Question: Etching Tank? UV Lightbox? Really? That seems silly.
Answer: Listen, when you build systems on top of nonsensical self-imposed constraints, things get silly. Remember that this is a game where the main character can not only cut trees down with his bare fists, but also neatly cut them into planks using only his bare fists too.

Question: Having to automate Etching Acid is insane.
Answer: 5x ore processing is insane. Deal with it.

Question: The Refinery? That’s for fuels.
Answer: Yet it represents the concept of splitting the components of a fluid entirely well, so in my opinion it makes sense for purifying molten ores too.

Question: The Refinery only supports 4 outputs. What if there are more than 4 ores in the modpack?
Answer: A valid concern. I can think of two ways to deal with it. The first: Redesign the GUI to put less emphasis on there being this arbitrary cap of fluids - perhaps a vertically scrollable grid of cells, where each cell represents a specific fluid. Otherwise, just keep it as-is and divide the mineral content of the input in equal parts across the output. Then take the outputs that are still impure and cycle them back into the input.

Question: Why are there no gems in this ore processing system?
Answer: Diamonds, Redstone, Emeralds and Lapis are already renewable in PNC:R. For Diamonds, use a Pressurized Spawner to spawn Wither Skeletons, then have a Drone autocraft the Coal into Coal Blocks, then convert the Coal Blocks to Diamonds in the Pressure Chamber. For Redstone, use a Pressurized Spawner to spawn Witches. For Emeralds, use a Vacuum Trap to absorb a Pillager Raid, then use the resulting Spawner Core in a Pressurized Spawner (or just sell stuff to Amadron). For Lapis, buy it from Cleric Villagers/Amadron.

After reading HipHopHuman's idea for ore multiplication, and desht's section on it, as well, some thoughts I had.

First, the mod is about compressed air, so some sort of sand blasting immediately comes to mind. Also, just like the Slurry, you could just have a Metal Dust item with tags on it, as well.
Second, perhaps an upgrade for the Assembly line system, using different drill bits for the drill. The drill bit you use could have a higher chance for higher multiplication.
Third, maybe drawing a vacuum on a pressure chamber could sort different small/tiny piles of ore dust from the Metal Dust item.

So it would look basically like:

Drill Ore in Assembly Line, receive 1, 2, 3, or 4 (or even with percentage chances) piles of Metal Dust based on Drill Bit. Also, can drill Gem Ores into their respective gems, with varying degrees of success.

Sand Blast Metal Dust to receive Refined Metal Dust

Vacuum Metal Dust to receive Small/Tiny Specific Metal Dusts, with varying chances. From an Iron Ore, for instance, you could possibly get Iron Dust, Small Iron Dust, Tiny Copper Dust, Tiny Gold Dust. Compress the Tiny > Small, Small > full size Dust in a compression chamber, smelting full size dust grants an ingot.

@HipHopHuman some very interesting ideas (I like the idea of mixed metal fluids, for example). Now some questions/comments :)

Generally:

1. Your examples talk about Iron and Gold specifically, but this would need to work for potentially any metal ores in the pack. So there needs to be a way of defining what metals any given ore breaks down to (e.g. you have Iron Ore -> 75% Iron, 15% Gold). And that way should probably not be hardcoded...
2. Would also need a colour table for metals for rendering purposes. I would not add a block for this Molten Metal fluid (so it won't be pourable into the world), but GUI rendering is a requirement. For impure, it might be possible to get clever with some colour mixing...
3. The stage 2 resource loop would need a bit of testing, especially in environments where a fast cobblegen is available. I think it could be workable, but there is the risk of it being too easy to cheese...
4. I really don't feel like reworking the Refinery to support more than 4 outputs, so the second option would be what's used there :)
5. While the use of NBT for the metal type is probably workable (and a good idea since we don't know in advance what metals are in this pack), I'd go with separate items for the type; e.g. rather than Metal Sheet (Impure, 75% Iron, 25% Gold), I would use Impure Metal Sheet (75% Iron, 25% Gold), where Impure Metal Sheet is a separate item from Pure Metal Sheet (although both items would use the same NBT tag format). This would be a lot simpler for recipe implementation.
6. Now I want to think of a way to automate renewable Lapis... (that's the one "gem" in vanilla that can't be automated by PNC...)
7. Some custom-coded recipes would be needed for ingredients/outputs which have NBT tags. But I think this could be made to fit in with the existing recipe system (similarly to how the existing Pressure Chamber enchanting/disenchanting recipes work - that's just manipulation of of NBT tags, in effect).

Specific points:
1/ii. Why 18 nuggets and not just 2 ingots? Feels like just making the player do extra crafting work for no good reason...
1/iii. Requiring a negative temperature (in conjunction with water) seems really weird. Wouldn't the water just turn to ice? :) Feels like it would make more sense to have a pressure requirement here (pressure-wash the ore).

2/ii. Why 75/15 here, and not 75/25 or 85/15 (or some combination that sums to 100) ?
2/iv. I'm a bit torn about using the Heat Frame Cooling mechanic again. On the one hand, it is an interesting automation challenge (although pretty much requires drones if using PNC only). On the other hand, it causes so much confusion to players who put a Heat Frame on a tank and expect it to work...

3/iv. -300C (aka below absolute zero) is an impossibility :) Also HFC bonuses work on a sliding scale, not a flat chance of a flat multiplier. So e.g. we could have a threshold of -50C, with a bonus of 0.02 per degree below that, and a bonus limit of 3 (for a total of 1+3 = 4 Metal Sheets). Then you'd have 1x at -50C, 2x at -100C, 3x at -150C and 4x at -200C...

4/i. Pressure Chamber air usage doesn't work like that. Actually compressing items doesn't use air at all; it's the insertion and removal of items that requires air. A requirement of 5 bar is also a bit problematic, since you'd either be running the risk of explosions, or be using Security Upgrades along with the annoying venting sound occurring frequently. Maybe require 4.5 or 4.8 bar here...
4/ii. Would require a bit of Etching Tank re-coding, since it doesn't use recipes right now, just a static process where an NBT tag on the PCB item is updated. Having said that, I have been considering more general Etching Tank applications, so...
4/iii. As for 4/ii. but for the UV Lightbox
4/iv. 1000mB of Diesel is a bit excessive, I think. And the choice of diesel seems a bit strange. Maybe Lubricant here (in a much smaller quantity, more like 10-20mB) ?
4/v. Again, -500C is impossible to reach, see 3/iv. for notes on bonus mechanics.

Temperatures are all internally stored in Kelvin, and never go below zero :)

Also preventing the heat frame from going on fluid tanks is already on my mind. It only goes because the fluid tank exposes an item capability so buckets can be piped in/out. What I might do is require that the block the heat frame is to be place on have an item capability but not have a fluid capability.

@desht I'll try my best to explain my thinking on all these points (with one eye too, since I basically almost had my eye gouged out in the time since starting this comment and finishing it lmao)

1. Your examples talk about Iron and Gold specifically, but this would need to work for potentially any metal ores in the pack. So there needs to be a way of defining what metals any given ore breaks down to (e.g. you have Iron Ore -> 75% Iron, 15% Gold). And that way should probably not be hardcoded...

Yes, that's the idea. This is my fault for not conveying it properly. So, the way I envisioned it working is that the resource being melted would become the "dominant" metal (so, Iron Ore results in a fluid that is mostly Iron content, melting Gold results in a fluid that is mostly Gold content, melting something like Osmium ore results in a fluid that is mostly Osmium). The remainder of bonus metals is just picked from the ore tags.

I also toyed with the idea that the percentages themselves are randomly generated. So, you could melt one Iron Ore into a (75% Iron, 15% Gold, 10% Copper), but then melt another Iron Ore right after that and get (75% Iron, 13% Gold, 12% Copper). If you were to store these two fluids in the same tank then they would equalize their contents and become (75% Iron, 14% Gold, 11% Copper), but that might be tricky to code, especially when you introduce the concept of mixing two fluids where one fluid has just one more metal in it than another... So it's probably simpler to just have the mod work out the percentage of each bonus based on how many ores are in the pack.

2. Would also need a colour table for metals for rendering purposes. I would not add a block for this Molten Metal fluid (so it won't be pourable into the world), but GUI rendering is a requirement. For impure, it might be possible to get clever with some colour mixing...

A color table could work, but sounds a little tricky to maintain? I think there are two other directions you could take here:

Method 1: Don't color the Molten Metal fluid dynamically at all. Just have all molten metal be the same color, or perhaps a different color for each tier of Molten Metal. Have it simply look molten, like this:

Method 2: Grab the center pixel of each ingot to determine the color dynamically. I think JEI actually does this in some areas, but if you want a smaller reference to look at, I remember reading that this mod does it as well: https://www.curseforge.com/minecraft/mc-mods/pulver

3. The stage 2 resource loop would need a bit of testing, especially in environments where a fast cobblegen is available. I think it could be workable, but there is the risk of it being too easy to cheese...

Absolutely, if you do implement this and need help testing I'd be happy to help out. I originally wrote the suggestion where Cobblestone couldn't be turned into Slurry, but I figured the resource bonus works well as a sort of "infinite ore generation" mechanic, and since so many mods have that these days I thought it'd be nice in PneumaticCraft. I personally am not a fan, but I included it anyway because years of playing with Botania's Orechid, Occultism's dimensional miner, the Void Miner, Extra Utils' Ender Quarry, etc has just conditioned me to expect some form of infinite ore generation.

I think the requirement of 2k Cobblestone for less than one ingot of output is expensive enough to be balanced when looking at it strictly from a PNC/Vanilla balance perspective, but you're right, fast Cobblestone generation methods could definitely be used to cheese it. Perhaps that feature can go away and it can just be a strictly resource multiplier system and not an infinite resource generation system. Or if you do decide to include it, make sure there's a config setting where the rates can be adjusted.

4. I really don't feel like reworking the Refinery to support more than 4 outputs, so the second option would be what's used there :)

I'll be honest I actually kind of like that. Adds an element of challenge.

5. While the use of NBT for the metal type is probably workable (and a good idea since we don't know in advance what metals are in this pack), I'd go with separate items for the type; e.g. rather than Metal Sheet (Impure, 75% Iron, 25% Gold), I would use Impure Metal Sheet (75% Iron, 25% Gold), where Impure Metal Sheet is a separate item from Pure Metal Sheet (although both items would use the same NBT tag format). This would be a lot simpler for recipe implementation.

I'd considered that, but wasn't sure which way was easier to implement. Whatever's easiest works for me.

6. Now I want to think of a way to automate renewable Lapis... (that's the one "gem" in vanilla that can't be automated by PNC...)

Lapis is already kinda renewable/automatable. Step 1: Defeat a raid, gain Hero of the Village status. Step 2: Stand next to a lot of Cleric Villagers and they'll throw it at your feet

Perhaps a funny way to automate it would be to give a drone Hero of the Village if it defeats a Raid and let the Cleric throw Lapis at it 😂

On a more serious note I'm not really sure what to do with Lapis...

Some custom-coded recipes would be needed for ingredients/outputs which have NBT tags. But I think this could be made to fit in with the existing recipe system (similarly to how the existing Pressure Chamber enchanting/disenchanting recipes work - that's just manipulation of of NBT tags, in effect).

Sorry, but I think I'm a little bit too underqualified with the more technical side of modding to understand that fully, but I think I get the general gist. Whatever's easiest or makes the most sense.

1/ii. Why 18 nuggets and not just 2 ingots? Feels like just making the player do extra crafting work for no good reason...

My logic here was that the nuggets are the metal pieces breaking off the sediment. You don't throw ore into a blaster and get ingots straight out of it. Create kind of does this with it's Gravel washing, so it seems established enough.

1/iii. Requiring a negative temperature (in conjunction with water) seems really weird. Wouldn't the water just turn to ice? :) Feels like it would make more sense to have a pressure requirement here (pressure-wash the ore).

My logic here was that the cold temperature ices up the sediment, weakening it's structural integrity, so that it can be broken down more easily. Heat would do the same thing, but it wouldn't create a slurry, as the water would just evaporate.

2/ii. Why 75/15 here, and not 75/25 or 85/15 (or some combination that sums to 100) ?

These are just examples. It could be that there is more than one bonus ore. It could be that there's no bonus ore. It should all add up to 100, since they are percentiles.

2/iv. I'm a bit torn about using the Heat Frame Cooling mechanic again. On the one hand, it is an interesting automation challenge (although pretty much requires drones if using PNC only). On the other hand, it causes so much confusion to players who put a Heat Frame on a tank and expect it to work...

I dunno, I kind of like the idea. It's already a mechanic in the mod that is used for little other than plastic cooling and perhaps making ice or obsidian. It already has a bonus multiplier mechanic to it. It seemed perfect to repurpose toward ore multiplication.

Are drones really necessary? Tube modules seem to do the job just fine?

Maybe the solution for the confusion/tank issue (even outside of this feature proposal) is to just blacklist tanks from heat frame use?

3/iv. -300C (aka below absolute zero) is an impossibility :) Also HFC bonuses work on a sliding scale, not a flat chance of a flat multiplier. So e.g. we could have a threshold of -50C, with a bonus of 0.02 per degree below that, and a bonus limit of 3 (for a total of 1+3 = 4 Metal Sheets). Then you'd have 1x at -50C, 2x at -100C, 3x at -150C and 4x at -200C...

So is Steve carrying 27641 cubic meter of solid gold in his pocket but here we are 😂 If you want the temperature to be more realistic, that's fine. I wasn't aware of the internals of the heat frame bonus calculation, honestly how the calculation is done doesn't really matter just as long as it goes somewhere in the range of 2x, 3x, 4x, 5x (even values in-between are fine)

4/i. Pressure Chamber air usage doesn't work like that. Actually compressing items doesn't use air at all; it's the insertion and removal of items that requires air. A requirement of 5 bar is also a bit problematic, since you'd either be running the risk of explosions, or be using Security Upgrades along with the annoying venting sound occurring frequently. Maybe require 4.5 or 4.8 bar here...

I see, Funnily enough I actually knew that but it slipped my mind when writing this... Perhaps limit the stacksize that can go in at a time? Or not, your call (if this gets implemented). As for the 5 bar thing, fair enough. It does make sense to have it just a bit lower than 5.0 bar.

4/ii. Would require a bit of Etching Tank re-coding, since it doesn't use recipes right now, just a static process where an NBT tag on the PCB item is updated. Having said that, I have been considering more general Etching Tank applications, so...
4/iii. As for 4/ii. but for the UV Lightbox

It would be nice to have more reasons to use the thing. I know PCB making is faster with the Etching Tank, but that Assembly Controller is just too convenient 😂

4/iv. 1000mB of Diesel is a bit excessive, I think. And the choice of diesel seems a bit strange. Maybe Lubricant here (in a much smaller quantity, more like 10-20mB) ?

So, this is actually where I drew inspiration from real-life pneumatic ore processing systems. They inject a hydrophobic gas into the froth flotation machine to cause the bubbles to push the ore content to the surface through a vortex. Diesel is not actually that hydrophobic, it absorbs about 100 ppm of water. Kerosene however is incredibly hydrophobic, but it's unfortunately non-renewable. Biodiesel is renewable, so that's why I settled on it. Lubricant.... It makes sense because it too is hydrophobic and renewable, but it isn't a gas. I suppose the idea could work though.

4/v. Again, -500C is impossible to reach, see 3/iv. for notes on bonus mechanics.

Alright, well, whatever makes the most sense then 👐

On the note of Lapis automation:

Lapis seems closely tied to enchanting in vanilla, so perhaps memory essence could be a part of the process. A little hand-waving transmutation. Copper is supposed to be stupidly abundant as well as has good conductivity, so it could make a good substrate for blue dye + memory essence. Might not be fully "set and forget" automatable - depending on what plays out with resource generation above.

e.g. Pressure Chamber: Bucket of Memory Essence + 4x Copper Nugget + 4x Blue Dye = 4x Lapis Lazuli + Empty Bucket, or, Bucket of Water.

I'd advocate for a way to use the Vacuum chamber to extract memory essence from enchanted books as well:

e.g. Vacuum Chamber: Enchanted Book + Empty Bucket = Bucket of Memory Essence

Hi, thanks for the suggestions. Some initial thoughts:

• Sifter: I'm actually already planning a drone-based sifting/fishing system with datapack support also utilising the loot table system. A default setup would allow fishing, with a fishing in water blocks, using the vanilla fishing loot tables. Modpacks could also add custom profiles with any block & tool combo and specifying any loot table
• Forge: Note that vanilla furnaces can already be used here: connect one to a PneumaticCraft heat source and it will smelt stuff for you (pretty fast and efficiently). You can use active sources like Vortex Tubes, or passive sources like lava/magma (but passive source need to be connected with a Heat Pipe to actually move the heat).
• Mill: At the moment this just sounds like a pneumatically-powered version of other mods' pulverizers/sag mills/etc. If an ore-doubling mechanism is added, it needs to be something a little unique. The other issue is that mods which add ore-doubling system also tend to add (and require) lots of custom ores which they also add. PNC:R doesn't add any custom ores, just using iron and (a little) gold. So there needs to be both an interesting mechanism and a need for those resources which are being multiplied. It's these reasons which have stopped me from adding such a system already...

Not 100% discounting your ideas, they're good, but not convinced about them yet. So feel free to convince me :)

• Fisher/Sifter: That sounds awesome! I've been playing with drones more lately, and I think your idea is both easier to implement and more fun. If I'm understanding that correctly, a sifter-mode for the drone would "fish" loot from dirt/gravel/sand blocks? RNG for nuggets, clay balls, bones, and the like?
• Forge: Good to know, haven't done this yet, will try it out later - and it does make my forge idea almost entirely redundant, lol.
• Mill: That was the general inspiration for the idea, yeah. Hmmm, ok yeah, I'll go back to chewing on this idea then.

Just to summarize your concerns regarding ore doubling to see if I'm understanding/interpreting them correctly:

1. PNC:R doesn't require extensive resources, so doubling isn't "necessary"
2. Most ore-doubling methods use intermediary resources, which is a coding/modelling investment that would need value-added beyond mere intermediary steps.
3. You're looking for something more unique. Could this mean a multi-block setup, or assembly-line setup, or a mix of the two even? You mentioned the Extractor from Rotarycraft was an example of an interesting idea.

1. Yeah... mostly. I mean, being able to double vanilla resources is certainly nice, but PNC just isn't a very resource-hungry mod these days, at least when it comes to vanilla resource (it used to need a lot more iron than it does now) - plastic and lubricant are more likely to be the pain points.
2. I would not want to be adding some kind of crushed ore items just to support other mods, no. What I would be open to (if it's doable) is a discovery process where other mods' ores and ingots can be matched up. Item tags could be useful here. One thing I might do as a "ore slurry" fluid, not placeable in-world, which can use NBT in its fluidstacks to determine what type of ore it's from. I had some thoughts about that here: https://gist.github.com/desht/b604bd670f7f718bb4e6f20ff53893e2#ore-smelting
3. See the gist I linked :)

Oh, and yeah.. the fisher/sifter would work something like that. We've been discussing that in #772 if you want to find out more...