This is a remix of kami's squashball USB extender, but with Vektor's original foot, as I don't have any T nuts or screws
Not sure if this a good model, my first try editing an STL, please give suggestions :)
3 perimeters, 20% infill, supports needed, print on its side.
I highly recommend you enclose the USB extender before inserting this into the 3030 rail.
Specifically designed to fit this 90° cable (UP -USB 3.0 Male to Female variant), but will work with other similar cables too like this one (tested & works).
Put the cable into the large part, close it with the top and push it together. It will require some force to close, so you can use a hammer or any similar tool.
To insert the entire assembly into the 3030 rail, you need to bend it a little bit. Push the bottom part first then hold it and slide the side in place, all will click in and you're done.
The author remixed this model.