The PLA Spring Motor Demonstrator was originally designed as a “proof of concept” tool to test whether a 3D printed PLA spring could power a gear train and possibly move a vehicle. The test was successful and a number of 3D printed PLA spring powered vehicles followed. This version has a 1 (drive) to 125 (driven) gear ratio in three gear stages.
It is a fairly easy to print and assemble, and makes a fun classroom demo.
You can use this as a springboard to challenge your STEM students to design their own 3D printed motorized creations.