I've fretted both my fiddles (4 & 5 string) with lute-type tied frets using 16lb fishing line & it works a treat. If the fret is out, just jiggle it round a bit until it's in. These are first-position frets and get looked at askance by other fiddlers, but I'm long past caring really - having played fretted instruments all my life (bass, saz, crwths, vielles etc.) this makes perfect sense to me but the sound of your actual fiddle is a joy to me. My Black Sea Fiddles (Karadeniz Kemence / Pontic Lyra) remain unfretted; I've tried to figure out a way of playing the fiddle like a Black Sea Fiddle, with certain ergonomic devices added below the neck, but with little success as yet. I figure once I've cracked that then fiddling without frets becomes a distinct possibility. I'm also presently coverting an old fiddle into a diatonic key fiddle along the lines of the Moraharpa; nothing beats the sound of a bowed string stopped by a wooden tangent!

Conversely, my wife presently has her eyes on a fretless banjo...