Summary

Rope pulley

The pulley diameter is 31 mm with a 6 mm groove. It uses 2 bearings for a smooth operation. The rope on the picture is 5 mm and runs very nice through it.
It is possible that a bit of sanding is needed to make the bearing fit in the pulley.

Parts to print:

2 sides
1 ring
1 pulley

I printed them with (transparent) ABS 0.3 mm at 90% fill. Will also work with PLA or other plastics.
No support is needed. The pulley wheel has a designed in support. You need to break this out.

Other bits needed:

2x M4x25 (shown on photo. They just fit without washers) or M4x30 (better) bolts
2x M4 lock nuts
4x M4 washers (optional)
2x bearing 624ZZ 4x13x5