[thechansen]

What is rigid, customizable, fairly cheap, and fun for adults and children? Lego building blocks. Just use something to seal the blocks and it will be plenty durable and just glue some foam to the inside of the enclosure for extra protection. Plus the Lego Digital Designer program which is free from Lego (Windows and Mac) will tell you exactly what you need to build your design and let you buy it right from them. Here's the PDF of parts for my prototype. I can't attach the actual lego file but if my measurements are correct this should fit the reader with the stock case.

EDIT: I figured out how to save the instructions as an html file, so in the zip it's the parts list, the instructions and any images included. My first time using the Lego Designer app so I wasn't sure if I could. And ideally I would build the case using all black pieces, Monolith style.