Auto Eject Paper Towel Holder (and mechanical towel sensor system)

This paper towel holder uses rubber bands to launch an empty roll of paper towels when the mechanical senor disengages from that last paper towel being pulled. Its heavily inspired by the M1 Garand rifle launching its empty clip when its last round is fired. While this specific design doesn't add much practicality other than maybe helping siblings/roommates remember to replace empty rolls, the general mechanism can be implemented in many ways (Example: fully mechanical auto reloading paper towel dispenser). The build is pretty simple on this however you will need to mess around with the strength of the launching and retaining rubber bands to find a balance of low friction on the paper towel and enough power to launch the roll. I will make an overview/build guide video soon. I heavily encourage remixes of this design. If you have trouble with the build I recommend checking out the f3d file as it has the model completely assembled.

EDIT: 7/22/2023 Assembly/overview video PLEASE WATCH BEFORE BUILDING

EDIT 7/23/2023 Cap plate and holder files updated for tolerances and easier tuning as well as file fixes and complete stl file added for display and .step file added for editing on more software.