I designed this simple Mount to dock my OWC Thunderbolt 2 dock under my desk. It has a small shelf on the backer piece and a front support that dovetails in for the front, the friction fit seems to keep it from falling out when my desk is jostled and things like that.
I imagine this will fit several docks, not just the Thunderbolt 2 Dock.

Print instructions

I printed in PETG at 0.2, with minimal infill. would probably do fine with PLA or anything else. The GCODE File that is included has a slow (10mm/s) first layer. I've found that it is helpful for bed adhesion with PETG on my machine.