Hi! I used four melamine boards that are 24 inches by 48 inches for the walls. For the floor, I had the hardware store cut a four foot by eight foot piece of wood in half and use one half for the bottom (for a variety of reasons, this wasn't melamine, so I covered this wood in self adhesive tile and contact paper since Plastikote isn't available in the states, really). I just screwed it all together and made a huge cube, so it wasn't too difficult. The most difficult part was getting all the supplies together, really!
For the lid, I just used wood glue to make two squares for the lid and stapled hardware cloth to them and attached them via hinges
This is the first thing I've ever built from scratch, so it was very much cobbled together as I went along.