Portable glasses case (4mm)

thingiverse

The same design should work well with 4mm plywood or MDF instead of thin aluminum sheets. This will add a bit more weight and stiffness to the structure, which could be beneficial if it's going to be used in a more rugged environment. Just keep in mind that you'll need to use screws instead of rivets to assemble the frame, as they won't hold well with thinner materials like plywood or MDF.