About this 3D model
It's a work in progress (missing pedals and seat) but works as a toy with my kids. Printed %100 scale and used toothpick as a pin for the wheels and tiny tab of super glue. Cut excess and sand it. If you have access to sheesh kabab skewers, you could try printing at %200 scale :P I printed in PETG, it was not easy to clean up. I recommend PLA+ for easier work. It requires supports for fork, handlebar and frame.