GT2 belts, which have a width of 6mm, are widely used in 3D printers and CNC machines. They work well with the popular GT2 pulleys.

You can use these DIY belts for projects that involve stepper motors or GT2 pulley systems that don't need high torque or speeds. Like this fish feeder project for example:

I have included various sizes, ranging from 70mm to 200mm in diameter.
Feel free to resize these belts on the Z-axis, if you need a different width.

These belts are meant to be printed with TPU filament: I tested with Overture High-Speed TPU 95A