We made custom pulleys using some acetal we found at a local plastics company. With several lathes and willing students it took some time but the learning experience was valuable. Not the most efficient process for making polycord pulleys but we liked them. Walking out is an issue but we wrapped some cable in between our pulleys & wheels to fill the space so if they walked out they would still function.
I was a fan of how
188 did theirs. It looks like they just cut a groove into some of the colson wheels from vexpro.