This is a mounting plate for a Circuit Playground. With stand offs you can attach a rotary encoder, or use the bottom plat with the nut holes to create a clamp to easily attach and detach wires to the circuit playground without bulky clips, wire wrapping, or soldering. 

First share, OpenScad files available. I forget if this one is 2mm holes or 3mm holes in this 3mf.
In the Scad, bolt= adusts the radius of the bolt holes, and nut= the face to face width of the nuts.

I used this to create a custom mouse with x,y,z accelerometer based navigation, and zoom for a scad project.