Here's a custom pulley I made.

Above are double stacked pulleys front and side views. One disc on either outside part and one disc in the center that splits the two bearings up. I have to add a black string across the bottom to prevent the yellow rope from skipping over the center pulley disc and hopping into the bearing next to it so that both ropes are sharing the same bearing and rubbing on eachother. That's bad. So a black string running across the bottom will make that jump impossible. So still have to add that. But overall, as long as tension is kept on this setup, it works well. I've tested it and it is working nice and smoothly. Still needs more testing but so far so good. You can see that all my knots and strings are coated in super glue. This is to prevent the knots from untying and just solidify everything more. The clear plastic discs are made from plastic cut out by hand from blueberry, strawberry, and sushi containers from the produce section of the local grocery store. Cakes also have this kind of plastic. It is firm but flexible with great memory to bounce back to prior shape if it is bent temporarily out of alignment. Pretty decent and nice and thin. I like it for this. I think it's less likely to break than a 3d printed disc. I cut it into these tiny discs just by eye with 4" straight titanium embroidery scissors.