Minecraft players should start by digging 12 blocks. Then they can hollow out the area they want to farm.
Three beds should be kept at one end of the room. Slabs can be placed in front of those beds to fill the remaining area.
Place three slabs a block away from the wall at the other end of the room. On the wall, place two blocks up, three more slabs across.
Place the zombie in a "cage" or, if the farm is fully alive, drag it by boat, minecart, or other method.
Scared Minecraft villagers will cause iron balls to drop and then flow into the lava, dying and dropping items into the hopper. Iron and Rose will appear in Minecraft chests.