this schematics only works in slime chunks, so you'll need to plan a reception with campfires at the bottom of the farm to collect slime balls. the schematic takes 7 minutes 45 to build with the create cannon. the slimes appear from layer -64 to layer 40. the schematics I propose allows you to place them one on top of the other, beyond layer 40 they will be useless due to the natural spawn of the slimes.
- 8 glow block - 8 slab - 4 wall - 2 torch - 828 block (12 stacks and 60).
don't forget the iron golem.