I have designed this holder for the IRC Tramp VTX, because I could not find any solution that would give it a secure, "flat" support".

I decided to trace the electronic parts and cut out placeholders for a tight fit.

Please feel free to add some improvements:
https://github.com/wojked/tramp-vtx-holder
(work in progress, dirty code, not nicely parametrized yet)

I have taken a photo of the Tramp VTX and identified the objects that prevents it from staying
securely flat on the "shelf". Those parts were not included in the extruded part.