A holder for the hex key (wrench) that fits the M3 screws on my MK3S (maybe MK3 too).
It aligns with two pre-drilled/threaded holes in metal riser frame.
I used two M3 screws from the “spares” bag.
Handy since the printhead screws need that key to adjust the idler tension, clear jams or change the nozzle.
The parts are identical except for the center hole size. The tight version is pretty tight when I used FLEX. 10% infill seems fine.
The author hasn't provided the model origin yet.