This is used to provide strain relief for wires on 130 and 180-size motors, particularly for my Nerf tricage, since motor endbells are facing out into open space, and it is common for wires to become detached, and wires are hard to run neatly.
I recommend trimming this to length, assembly requires 2 x #2-1/4" self-tapping screws, commonly found in Nerf blasters and other plastic toys. Your printer absolutely must be dimensionally accurate, otherwise you will be doing a lot of sanding and drilling.