The plugs that hold my bar tape on the drop bars on my road bike fall out every once in a while, and the replacement ones from the bike shop don't match my bike. So I designed a new one! I printed one in blue that I was able to take to class, and printed a set in red for my bike.
3D Printing and Post Production
The biggest problem was that the 3D printers, (or my file) weren't creating the support structure my model needed. Second, the plastic used to create the original plug was much more flexible than the materials available. So instead of it flexing to fit, so despise modeling the existing plug to .01mm, the first one I printed snapped when I tried to put it in my bike's drop bars tube. So I printed another, and Dremeled down the inner cylinders to fit better.