Composter is crafted from seven wood slabs arranged in a U-shape on the crafting grid, yielding one block per recipe. The crafted item is a sturdy wooden bin with an open top that accepts compost-eligible items via right-click — most plant matter qualifies, including saplings, leaves, seeds, food crops, fruit, and certain mushrooms. Each accepted item has a probability of advancing the internal compost level, with high-value foods like cookies and bread offering higher fill chances than seeds.

The block has eight visual fill levels. Once the seventh level is reached, the next valid item triggers the final state, after which a single right-click harvests one bone meal item from the bin and resets the level. This mechanic creates a renewable bone-meal source that requires no skeleton hunting and is the backbone of village-based farming automation: villagers with the farmer profession automatically use this block to convert their excess crop yields into bone meal, completing a fully passive farming loop without any player input.