I recently got a wood lathe and have been experimenting making my own wooden knobs. After making the knobs, I drill them out and put an insert of aluminum with a drilled and tapped set screw on the side. I found some aluminum tubing that fits normal pots, but I'm having trouble finding stuff for stacked pots. I have a bass with some pre-made wooden knobs and they have aluminum and brass inserts. I'm not sure if the luthier made those himself or bought them. I made some inserts from wenge for now for the stacked knobs, but I would much rather make the inserts from brass or aluminum to hold the threads for the set screws.
For those of you who make your own knobs, what do you use for the inserts? Is there a supplier of aluminum or brass tubing, or pre-sized inserts, that are made to fit the pots exactly?
A few pics of some of the knobs I've made so far (the multi-layered knobs on the bass do actually match the body, the lighting in the pics just makes it look like they don't...they are made from the leftovers of the body wood laminates of the bass):
Some wenge and padauk knobs: