This belt is not meant to be a fully functional replacement part, I tested it with TPU and it works, but a proper S3M timing belt is cheap and it should work for years.

That said, I designed this part under the national lockdown for COVID-19, as I wanted to use my old bread baking machine which had been sitting unused in my basement for 8-10 years.
The rubber in the original drive belt did not age well, it dried and crumpled apart the first time I ran it.

I tried to design and print one out of TPU, I guess other DIY solutions could work too, but after a couple design iterations to take account of the shrinking/measurements/flexibility I think I found measurements that work reliably enough.

I have been using the machine daily for a couple weeks now. The belt rarely slips, the tension is constant, there is a slight mismatch in the spacing of the "teeth" so it skips a few steps every once in a while, especially when the motor has to push a bit more on the dough. If it were to break i could just print another.

This is not a 1:1 replica of the original belt, some tweaking had to be done to accomodate for my printer, more on this in the 'print details' tab.