"I've sold hundreds of 3D-printed license plate mounts for various Porsche models. These feature heat-set metal threads and 3M Molding Tape to hold them in place. Demand got to be so high, that I now have the standard black mounts CNC'd out of solid ABS, but still print them in special colors for people who want color-matched mounts."
One of the more common ideas customers have had was adding skate bearings to our acrylic spool holder, so when the supply of acrylic rods ran low, it was a no-brainer to convert the spool holder to use skate bearings instead. Keep in mind everything we design has to work in our print farm. The spool holders are specifically designed to require no adjustment or maintenance and just work day after day and month after month. Any changes to add skate bearings couldn't affect the practical functionality.