Interesting toy. Might have to look into one. I've been using tin snips and a bench grinder to do them, and then a hand clamp to bend or make a jig from hard wood. The latter is basically a couple of slots cut into the wood. Insert the lip until it sits square, and then bend. I picked up one of these:
http://www.grizzly.com/products/Port...nd-Punch/G8780
to do the holes. Much easier/quicker/safer than using the drill press. Round holes. Do the hole before you bend the lip.
Jigman