I saw a YouTube short showing these off and they looked handy. The design calls for some nuts and bolts which I don’t have any kits, so purchased this one which should come in handy for future projects too. Creating two better knobs, two caps, a body, and a holder will require 20g PLA filament, a 1" thick sandpaper strip, two M4x20 bolts, and four M4 nuts. I ended up Gorilla gluing the bottom nut. I used so much that it impacted the fit of the caps and had to cut away at the solidified glue with a knife and sand the base flat. I also labelled them with their grit using my Dymo I’ve been obsessed with.