This is a pulley I designed for the Tuco Flyer project, a robot made of several winches that operate on nylon paracord. I couldn't find a suitable pulley designed for light-duty loads to run smoothly on this diameter of rope, so I designed one. The pulley itself runs on two 606 skate bearings over an M6x40 bolt, and the housing is held together by two M3x35 bolts and nuts.
The pulley housing is designed to accept two loops of paracord that each pass through both halves of the housing, additionally holding the housing together and acting as a failsafe so that even if the 3D print fails, the paracord looped through the pulley will be retained by the paracord holding the pulley mount together.
The pulley is printed without support, but the overhang is quite severe and I had to run my printer a bit slower than usual to give good results.