I've been thinking about this for a while and really feel like this sort of crafting mechanic might fit well with the pneumaticcraft style.

My idea is a large multi block machine similar to the pressure chamber. It would take pressure to run the printing arm and also require an internal vacuum in the chamber to approximate the neutral atmosphere that is used in sintering processes.

So the machine would accept a variety of metals in dust form (or simply converts them to a dust form as some mekanism machines do for their secondary inputs). It would then allow you to choose the output from the machine's gui. Once chosen, it'll keep making that part continuously until it runs out of resources.

I know this sounds a lot like most auto crafters, but there's a fundamental difference that is important. Everything you make can potentially have the same cost without the need for weird recipe differences. Think of things like mystical agriculture dye recipes that are all arbitrary shapes just to deal with the fact that they're used to make all of the dyes.

Since the output is chosen from the gui and each item can effectively have the same cost, it kind of flips 3x3 crafting on its head. The output no longer being defined by a 3x3 pattern of items.

For example maybe a bit of iron dust would make a single iron bar. A bit more for a pressure plate. A whole pressure tank could be reduced down to a certain quantity of compressed iron dust.

Similarly, it could used to craft with plastics more efficiently. Maybe that pressure tank example actually requires 2 input types to craft.

The idea came to me as I am working on a mod pack. I wanted to find a way to simplify some recipes as I had realized that a lot of the different materials added by others mods is largely done as a means of dealing with the limited number of meaningful recipes for crafts. I think Thermal Series is an excellent example of how silly this can get. Each dynamo has a basic recipe template that consists of a couple ingots, a couple gears, and a machine frame. The ingots and gears are the only thing that really changes, and so to be able to craft all of the dynamos, extra materials are practically required to differentiate one from another in the 3x3 grid. With the 3d printer model, however, all of them could have identical material costs and a lot of the extra materials wouldn't need to exist (tin and gold make for bad gears anyway). This then reduces some of the bloat needed in packs.

A crafting mechanic like this could allow me to streamline cross mod integration greatly and also add quite a bit of cost to the crafting process (a plus for me) as you'd need a fair amount of infrastructure to run these crafting machines.

If you're interested and need any clarification, feel free to hit me up. And if it doesn't interest you, well, thanks for reading anyway!

Had another thought for this, specifically for controlling the output through redstone.

If the multiblock had 2 redstone ports on it you could feed them different levels of redstone to send a signal to control which item it'll craft.

Basically I'm thinking it could be a nice way to integrate with something like ae2 or refined storage. Or even allow the player a means of creating a neat redstone interface to dial in their craft.

I like this a lot, but it's a major feature addition, so probably not before 1.14...