Making a fretboard from a fretboard blank is a work of precision with some specialty tools involved. Next to a nice piece of wood you will need a fretsaw and a radius sanding block. If you don't have these tools and only want to build a few necks you might want to consider a pre-slotted fretboard.
Pre-slottee fretboards are available for guitar and bass, in various scale-lenghts and radii. The fingerboards are oversized which make them suitable for most guitar or bass necks.