@Tulio, I have a large quantity of 13mm steel bearings (from a magnetic construction kit) that I would like to use. Should I print all the parts with the ratio 13/9.5 so that your design will work with the bearings I have?
Great design, BTW. I've always liked the ball run gadgets people make and post on Youtube, so now I can have my own. I'm planning to automate it (from the bottom - wood base). Thanks for sharing!