Improved tightening knob

Knurled version of knob, expanded 3% for improved fit on threads.  I printed it at 0.15mm layer height with a 0.40 print nozzle, no support.  I used a 20% gyroid pattern, but most strong infill patterns would be fine.

I like to knurl things for easier grip, so I imported the knob STL, filled it out, knurled it, and then expanded it 3% for an easier fit around the threads.