Fortunately for all you impoverished Steves out there, you can build a similar machine pre-soulforge. This design is much cheaper (about 2 gold ingots: 3 sticky pistons, 1 turntable, 2 repeaters). I do not possess Dawn's ability to shrink complicated machines into impossible spaces, but I suppose this design has a lot of room to be improved upon and compacted.
Imgur album:
https://imgur.com/a/FvrkyJN
Here is the timing sequence if anyone wants to try making it themselves:
1: The dispenser releases a bottle or zombie flesh (by limiting the flow of items into the packing chamber, you ensure that there can only ever be the perfect amount of flesh or less for packing, since any blocks that form are removed from the machine immediately).
2: The piston shovel comes down to harvest a block if one was made.
3: The packing piston on the bottom pushes the dispensed item into the packing chamber, and the valve piston on the left closes to make the chamber packable. If the right number of flesh is reached, a block is made.
4: The valve piston retracts. The packing piston also retracts, pulling a newly packed block with it if able.
5: This is sorting part! The valve remains open, but the packing piston pushes again. This does nothing if a block wasn't made. If a block was successfully packed, however, it will push any bottles out of the open valve on the side, cleaning out the packing chamber.
Repeat! Profit!
I am not a technical person, if you can't tell, so lmk if that doesn't make sense. A video would probably be better, but half of the fun is figuring out this stuff yourself. I will be adapting this build to my survival world soon, so I will post pictures when that project is complete.
Another note: this probably shouldn't be used for separating creeper oysters/witch warts, since those items are rare drops. They will probably despawn in the chamber before you can get enough to pack a block.