Always thought that it would be nice if the Essentia Reservoir from TC4 could make a return to give another option for essentia storage since currently there are only jars. I know that the essentia capacity per jar was increased to 250, but that is sometimes still not enough storage to do what you want and you end up with an abundance of jars, or many jars with small amounts of essentia. If this gets implemented the amount of essentia it would contain would be 1000 to match the originals 4x storage of 256 essentia.

I know that thaumic additions has the mechanic where you can "upgrade" jars but that does not fill the niche of the TC4 Reservoir since you still cannot mix different essentia. Other than that mod with its jars, I don't believe there are any other ones with any other form of essentia storage than just basic jars for TC6.

The second idea is from Gadomancy for 1.7.10, Sticky jars that allow you to place them sideways on walls or upsidown. Most useful for people who use essentia tubes instead of golems/by hand. Crafted with a slimeball and the jar. The mod is no longer in development and hasnt been since 1.7.10

Let me know your thoughts or if this not possible/difficult to even program.

Revamped TC4 Essentia Reservoirs are an idea we discussed, and while it's something we do want to add I can't really say when it might be added, since we want to work on other things first. As for sideways jars, that's another reasonable idea although it can get dodgy to directly copy ideas from other mods, even ones that are long abandoned (just look at the drama that surrounded mods trying to recreate Witchery for instance).

We were thinking of adding a reservoir like thing, but we wanted to make it more interesting than just a mass storage thing. It's still far off given the amount of other stuff to do, but the basic idea was that the essentia inside would mix (think of metals mixing in a Tinkers' Construct smeltery) and potentially do bad things if two or more opposite / conflicting aspect types came into contact with each other. The capacity would be around 1000 as you said. If we did do this, it would be a good idea to clean up / refine the current list of aspects that don't like each other that the elemental resonator uses, as that is what would eventually be used for this.

Edit: by metals mixing I mean having them all together in 1 container, not alloying or anything like that - essentia will still be separate and able to be extracted individually.