Material for making Spinning Wheel Belts

Hey! I’m an old retired school teacher into making and rebuilding spinning wheels. The picture of your dad’s wheel caught my eye while surfing. I was told to make belts from O-ring material but was unable to find the stock. An old friend in hydraulics told me to try Window Screen Spline. I found it quite easily at the hardware store.
Simply measure the length that you need. I use a piece of cotton twine because it does not stretch. Feed it into the wheel crossing the ends. Mark, with a marker pen, from the end to where the string meets around the grooves in its journey. Use that to measure out the amount of spline that you need. Cut the spline with a sharp knife or scissors at a very extreme angle on both ends. They will fit together well and have more area for super gluing. Glue the ends together and Voila!, you’ve got a belt. This material is taunt, non-stretching, grabs the wood well for pressure and friction and the material is very inexpensive. I hope this info will help your dad and others.