Extension for the USB plug.

Specifically designed to fit this 90° cable (UP -USB 3.0 Male to Female variant, see the picture), but will probably work with other similar cables too (like this one).

You don't need any additional hardware. Remove the modeled brim. Put the cable to the bottom part, close it with top and push it together. It will require some force to close, you can use a hammer or any similar tool. Insert it to the 3030 extrusion facing upwards and turn it carefully 45° to the front. The bottom bevel should lay flat on the surface.