If you want something challenging, here is a cool YZR-M1 Bike Papercraft that you can make by Yamaha Motor. The real model is specifically developed by Yamaha Motor Company to race in MotoGP series from 2002 till present. It's is kinda complicated so be ready because it will consumes your patient and time for sure. Beside this YZR-M1 paper model, there are many more bike that you can find at the site.