I designed this to create a mounting point for a Trim indicator gauge on my boat.  It mounts to the interior side of the display console.  It is a poor photo I took right before covering it for the night, but actually mounts the new gauge clear of the other gauges when seated in the captains chair.

It is sized to hold any standard instrument cluster gauge like water temp or battery.

I did a rub with a pencil on a paper template to locate the screw holes, then located the paper template on the mounting surface and used an awl to mark the screw hole locations. and added a larger hole  in the center for the wiring. 

I printed this in PLA, but ABS would be more appropriate.

Just print it with the back flat to the build surface with no supports.