A customizable, weather-proof pulley, in three pieces for easy printing.
Block pieces feature male/female interlocking components, to be secured with with M4 bolts. Wheel axel is plastic, backed up with M4 bolt. M4 bolt length will depend on rope diameter (which effects block thickness).
Use Customizer to control the rope diameter (ideally 5mm - 16mm) and wheel diameter (ideally 50mm - 150mm).
A pair of these pulleys, plus some clothesline, and my daughter now has a house-to-treehouse food delivery 'zip line'...
UPDATE: A minor update to the .SCAD to include some 'friction bumps' to improve wheel tracking.