For the school maker fair, we used Tinkercad, Cura, and the Ultimaker 3D-Printer to design, perfect, and print a fidget spinner. We then put bearings into the corresponding holes and presented the spinner.
A fidget spinner relieves stress and was originally made to help people who have ADHD, anxiety, or autism. Fidget spinners might have been invented in the 1990's (WOW!), but they became popular in 2017 - that's why we were inspired to do this project. Some teachers even supply them for their students!
We used the design process to prototype the spinner, test it, and iterate. At first, the holes were too big so we took the diameter of the bearing (2 cm) and made the correct hole size. In this process we learned how to print the correct sizes. If we had more time, we would have added weights to the spinner to make it spin faster. If you want to complete this project, my advice is to put a lot of time into your design for the best performance. Time pays off.
Price: 1-5 dollars (depending on bearings)