Minecraft wiki entry for Furniture, associated text: Lay down 5×3 wooden slabs. At the two long ends, make a 3×1 fence. Cover the whole lot in green carpet/rug. In the middle of the long sides and at the side, place 3 high wooden blocks, with tripwire hooks on the inside of the top blocks, connected by string for the net. Cobwebs might work here as well. But you may not be able to get the green carpet in that case just use green wool.