Duplo compatible train wheel rim
thingiverse
I was too lazy to search for a proper o ring for the drive wheels and I'm pretty sure my local hardware store doesn't have something like this. Anyhow, here is a ring that can be printed with flexible filament as rubber ring replacement. Fits perfectly for me. Practical test is still open but looks good on manual tests though. Check out the original thing to build the train for yourself (or the ones you love): https://www.thingiverse.com/thing:2479704
Download Model from thingiverse
With this file you will be able to print Duplo compatible train wheel rim with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Duplo compatible train wheel rim.