A block that, when activated by redstone, can place or break blocks. This has probably already been suggested, but the placer would look kind of like a dispencer and would place a block directly in front of it. A breaker would break a block at the same speed your hand would, and would not drop stone-type blocks or glass, unless you put a tool into it, then it would break at the speed of the tool, and it would damage the tool. It would be expensive, so it wouldn't be too op. It would drop the block that it broke with the drop entity, and can be collected with hoppers. This could be used to make auto-harvesting tree farms, and it could place block to make an auto-house. What do you think?