Just to expand the belt talk further, has anyone used dental floss (unwaxed) as a TT belt? It was popular here in the 90s and when Dr Forsell came over and demo'ed his Air Reference with dental floss as belt, I tried it on my VPI but I didn't seem to like the effects. And also I guess the fit is not snug as my motor cannot be pulled away like the Forsell's separate motor for a tighter fit.
Our dear departed friend Atty. Jun used dental floss on his TNT. Honestly I couldn't tell the difference. I never tried it myself. I don't know how to tie a flat knot. The thought of having even just a tiny bump on the belt turned me off of the idea.
Tony Ky Ma here at WBF has been doing trippy things with threads as belts.