This is a mounting bracket and stand for the AC Infinity AI-ATC intelligent fan controller. It can be used hanging from above or as a stand, as shown in my photos.
It's pretty over-engineered for what it is, complete with countersunk holes shaped for the hex nuts that come with the AI-ATC. And there's a subtle tilt to the bracket so the face of the controller sits a few degrees back from perpendicular to the surface.
I built mine at .28 mm resolution on a AIO Robotics Zeus printer. It fit perfectly! Be careful with the screws and bolts, though, since a bit of over-compression can cause PLA to crack.
Also, check out my 80 mm fan shroud!
I imagine folks might be able to modify this for all sorts of other panel-mount things. Enjoy!