There's a 20-chapter DVD on the market instructing DIYers on how to build a flight case. Luckily, thanks to the internet you probably don't have to buy it—there's an excellent DIY flight case online tutorial by Dutch multicreative Joris van den Heuvel right here.
Heuvel goes over the specific tools (jigsaw, pop rivet wrench, drill bits) and specific components (plywood, extrusions, corners, latches, hinges, handles, etc.) you need to devise a flight case, then launches into a clear ten-step guide for getting it done. Obviously you just alter your dimensions to suit whatever it is you're trying to box.
