After building a couple of mousetrap car kits I designed several of my own cars although it was basically two different major designs and then small variations. The latest mousetrap car uses a foam block for a chassis, coat hanger wire for axles, and CD wheels. This design works well but it was designed mainly to be inexpensive. The Doc Fizzix’s mousetrap cars use more expensive materials such as brass axles and lever arm which is better.
Almost everything I know about mousetrap cars I can credit to reading this book from . I highly recommend purchasing this book and also a mousetrap car kit from Doc Fizzix’s. After building a good kit car, designing your own will be much easier.