This is the half of a very cheap RPi case: https://www.amazon.de/gp/product/B00MQLB1N6/ref=ppx_yo_dt_b_asin_title_o09_s01?ie=UTF8&psc=1
Overall it is not a perfect solution, more or less quick and dirty, but the case fits without screws (it’s strong enough, that it holds without any pressure on it)
I have filed the cavity for USB-c socket a little bit withhelp of a rasp/file, because the cavity was too small for USB-c (was designed for the µ-USB connector of a RPi)
I put (glued) some small pieces of foam (pink pieces on the left side of the pictures) on the inner side of the case for better stability. It’s only necessary on the opposite of the USB connectors, as the USB connectors itself hold the case already in correct position.
The two fans are also glued with double-sided adhesive tape.
Maybe that gives you some ideas for your own customized solution.