Shorter belts using a belt tensioner
by peddiparth, published
You do not need the full size of belts for your 3D printer X & Y axis. Use a the zip tie belt tensioner to substitute the other half of belt with something you pulled from an old printer or scanner.
Ensure that the belt tensioner does not cross the Idlers on either side of your axis.
The trick to finding the right length of belt is to fold the belt at the axis mount point, and adjust the length if it is not right for your printer's axis.
I paired MXL belts I pulled from two old HP scanners to other belts from other scanners/printers for my X and Y axis on my Prusa i2.
I think this system will work for most 3D printer designs.