simple sanding block

Needs 2x M4 nut, M4 threaded rod ~32mm and optionally a washer.
Recommend 2mm thick rubber, strong foam or felt on the outside (160x35mm).

One of the nuts should be inserted in the knob: pause at the appropriate layer and put the nut in, continue print.
Other nut must be pressed into the slot of the body.

I cut my sanding paper 35 x 200mm.