The original rubber material on my original steam controller started getting all gummy and coming off on my hands from age. I designed and printed this new cap for the joystick. YOU MUST USE TPU! 95A works, but the softer the better  an 85 or 90A would be better and more grippy if you have it. I used paintable fuzzly skin on the rim.  I found the settings in the file to work best. If you go much larger with regard to the fuzzy skin parameters its too scratchy and if you go too low it gets too slippery. There are 2 design styles included in the file too, print either you find works better.  

Peel off the old stick material. I used a single edge razor to remove anything I couldn't get off by hand until it looked like the picture here. Then just snap the new cap on.