Or even just put masking tape over the board. I have fretboard protectors, which are great for one or two frets, or when fling/sanding down sharp fret ends, but I find it is quicker for a whole neck top tape the board up. I bought a pack of modellers masking tape in different thicknesses, so I don't need to keep cutting standard masting tape into thin strips. One pack will do many guitars. Stuff like this: