I've built them out of small deep freezes, and for small jobs like you seem to want to do, a big cardboard box works great. Use Saran Wrap for the window, it lasts as long as anything else and costs like nothing to replace. Dryer vent hose and gauntlet gloves work good and cheap, too. Get a box with a drop-on lid to be really classy, and put the window in the lid. I do things as big as wheels in one like that. Put a cast frying pan in there to do little stuff without blowing a hole in the box. Cleans the frying pan good, too! I had some 30" square plywood tea chests years ago, they were perfect.