I am a EECS student from UC Berkeley, and your 3D tractor impressed me. I came up with an idea of making a guitar out of spring-loaded retracting security badge clips. So I dissected my mouses and figure out the mechanism is similar to your project. If this portable guitar is built, not only will the users be satisfied, it will created more opportunities for people who wants to learn due to the cheaper price & more functionality...
If you are interested, please add me on fb & there are videos introducing my idea on my fb.
Thanks again for your time and I'm looking forward to hearing from you