This is awesome :) A massive improvement over the original belt mounting.
I had to sand the top edge to make it fit my printer as the screw holes were slightly too low to meet the threaded holes in the printer head carriage. After that, a great fit and easy to adjust the belt tension.
I sliced with Cura using horizontal expansion -0.2 but should have used more like -0.1 I think. Still does the job well.
100% infill for strength.
100mm/min print speed was good for the borders, 200mm/min infill.