Stackable moss bone meal farm

A stackable moss bone meal farm built as one module. A ring of eight lava buckets and two water buckets generates fresh smooth stone, a dispenser under the centre moss block bone meals it, and the moss spreads over that stone and grows carpet and azalea on top. Forty nine pistons and twenty nine observers sweep the growth off, water carries the drops down a run of stairs into nine composters sitting on hoppers, and those composters turn the plant matter back into bone meal for ten chests. The farm is directional, so check F3 before you start, and it wants a 30 by 30 area about 20 blocks tall. It works on servers and it can be stacked, with a second module roughly doubling the output.

The stone generator starts making cobblestone once the chunk unloads. Switch the farm off with the lever before you leave, or keep it loaded with an ender pearl stasis chamber.
To repair it after that happens, turn it off, break the cobblestone, put stone back, and check every sign is still in place.
Waterlog the trapdoor with the first bucket and put the second bucket on the next hopper beside the fence gate. Waterlogging the fence gate itself is what makes the water run through.
Water goes on every one of the stairs at 10:37, one missing stair stops the whole flow.
The farm is directional. Press F3 and match the facing shown in the video before you place the two droppers, wrong facing is the most common build failure here.
TreeTrunkGaming-qz8og built it on 26.2 and says bring about 12 more glass than the list asks for, and set up an infinite water source before you begin.