Belt for rock tumbler / ball mill

I've had a ball mill / rock tumbler sitting in my garage for years. I finally broke it out and the belt broke overnight. I had several replacement belts and even after adjusting the tension they all broke. I designed a simple replacement I could print out of TPU. So far it has been running fine. I think the previous belts were probably in rough shape after sitting in garages for 10-15 years but I'd rather just print my own. It doesn't have exactly the same profile so it wouldn't need any supports, and it is perhaps 2mm or so shorter on the outer circumference, but so far it's working fine.