I've done 3... the toughest was a polyurethane'd maple fretboard on a Precision... as it ultimately required a complete refinish of the board. A good source of 'fret-fillers' are the .020" or .030" maple plywood boards sold at a lot of hobby shops. I used the same as fillers on a rosewood Jazz neck, where the guy wanted visible markers.. that one was pretty easy, as the frets came out nicely. It's a good opportunity to true the fretboard, and I cautioned the 'rosewood' guy that it'd last a lot longer with flatwound strings. That one was about 4yrs ago, and he's still pleased with it.
Hi Mike- I made a bass fretless and I used .020 plastic binding from stew mac and one piece costs about 5 bucks and it comes in diffrernt colors too. i used their glue for doing binding to hold id in place, and then sanded the fret board to the proper radious and then put some DR.Ducks axx wax and the thing came out looking gr8.
Just another method for you to think about--
Peace,
Donald
Use 100 grit paper to sand the fret tops off leaving the tang in the slot. This keeps the slot under pressure and there's no need to pull the frets. Leaving the tang in also gives a very nice line where the note will be played.