Printed Solid manufactures awesome enclosures and the Prusa Mini version comes with an acrylic door with a finger-sized hole that is supposed to be used to open it. I've designed a knurled knob that fits perfectly in that hole and has a nut embedded into the print. If you print this, don't forget to add a pause (M601) instruction at the layer where the top of the nut starts filling in.
You will need:
The backing to the knob has a recessed cavity where you can insert the washer and the screw and is used to tighten the entire thing in place.
The author hasn't provided the model origin yet.