[Gdeaver]

1/8" steel pop rivets, T6061 1x1x1/8" aluminum angle and a drill will give you a tough box. 1/4" furniture grade birch plywood is tough and light. To kick the plywood up a notch laminate a layer of 6 oz. S fiberglass on one side with epoxy or real go for it and laminate both sides. Strong, lite and can be done with common hand tools.