My basic concept was to create a Lightning McQueen car that he could wear around his waist, with straps over his shoulders as support. I decided to build it out of corrugated cardboard, which I hoped would be sturdy, but still reasonably light (and obviously easy to work with). I had an old large box made of double corrugated cardboard which had plenty of material.
Once I had the basic frame, I needed to attach the top of car to the frame. I created two braces by cutting long strips of corrugated cardboard. Each brace was made up of two strips: 1 long enough to go between the sides of the frame, and a slightly shorter piece to fit inside the top of the car. I glued the two strips together, leaving small ends that I bent at 90