Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:5246210.
I wanted a way to charge the trackers, off the desk and without taking off the straps. Unlike a previous Vive tracker, there isn't a good way to "hold" onto the tracker if the bottom has something attached. So the USB port provides that mounting solution. The plastic here is just a guide to help me find the usb port. I imagine this could also work with magnetic connectors, I've tried to avoid them since I heard they burn out vr controllers sometimes.
As for the model I wanted something I could print without supports on a prusa mini. Though you might still want some brims if your bead adhesion isn't great. As for the USB, I just used hot glue. Held the tracker in position plugged in a USB and hot glued around it. Kind of messy but figured the hot glue would act as rudimentary suspension. So a misalignment of the usb and the holder, or the weight of the straps pulling on the trackers, the hot glue would take up some of the pressure.
This is the usb cable I used: https://www.amazon.com/gp/product/B08GY7FBHZ?ie=UTF8&psc=1&linkCode=sl1&tag=dsl07-20&linkId=b1df4c7ccf768937a23a809076241812&language=en_US&ref_=as_li_ss_tl