If you want to make a cheap metal box and you don't have a lot of tools you can still do it pretty easily. You can use 16 gauge aluminum sheeting for the sides and you can use 1/2"x1/2" angle aluminum to hold the pieces to gether. Just drill or putch holes and rivet. The alum pieces are even thick enough to tap holes so you can screw into them if you want removable sides. I made by enclosue this way but used aluminum diamond deck as the sides instead of just flat alum. It has a nice industrial look.