My son chewed the carriage link on the back of Thomas the Tank Engine when he was a baby. I recently bought my first 3D printer and was looking for something easy to model for my first design. When I realized the train could be easily taken apart to replace it, I decided to design a replacement part. 

I printed the part in the photo using a 0.2mm nozzle in PLA+ I don't think it would make much difference to print with a 0.4mm nozzle.