Automatic Cow / Animal Farm

Animal farms come down to one mechanic: breed two adults of the same species with their preferred food (wheat for cows and sheep, carrots for pigs, seeds for chickens) and you get a baby. Grow it up, breed it again. A working farm just needs a small pen, a steady food supply, and a way to periodically thin the herd, since animals will keep breeding until the pen's too crowded and stop on their own.

The simplest setup is entirely manual. Keep 2 to 6 adults in a small pen, breed occasionally, walk in with a sword when you want meat. No redstone needed, and honestly that's enough for most survival worlds.

The automated version adds a permanent kill mechanism the animals wander into on their own, often a lava block positioned so a fenced corridor funnels grown animals past it. Fire and lava kills leave cooked meat directly, no extra cooking step. A campfire works too, dealing slow damage without risking an actual fire spreading. A hopper floor underneath catches the cooked meat, leather, and XP.

A more controlled middle ground uses a dispenser loaded with a weapon, wired to a button, so you decide exactly when a kill happens instead of a passive mechanism running nonstop. Useful if you want to keep breeding stock alive and cull in batches rather than losing every animal that wanders past a permanent trap.

Cows specifically are the only renewable leather source outside fishing, which feeds books, armor stands, and item frames. A cow-focused version of this farm is worth building even in a world where food's already easy to come by.