Minecraft wiki entry for Piston_uses, associated text: By placing a row of three cobble, then on top of it, cobblestone on the left one, and piston (facing right) on the middle one, nothing on the third one and a hole in the ground at the end, one could create a lava garbage disposal. After following those steps, put a lava bucket in the 2 block deep hole at the end, and place a button on the top left block. Unwanted blocks can be 'dropped', using the Q button (by default), onto the top middle block, then, after pushing the button the little blocks are pushed into the lava. This device does not destroy placed blocks, only dropped icons of blocks. While it does demonstrate concepts of using pistons, and looks cool, this device is not as practical as most other incinerators and garbage disposals, which are much simpler. For example, you could make a small pit of lava and drop items in it manually. After adding a trapdoor, it is a safe efficient way to dispose of unused items. You could also clear out a plus 2 blocks down. Put sand in the center place a cactus and trapdoor and one that if you fall in, you can save yourself.