Did you mask, or freehand?
Neither, sort of.
I freehanded the round-overs up to just over the "edge" of the top. At that point I then run the whole body through the finish planer to get the sharp edge. This required some planning ahead to allow for the removal of that bit of top wood from the cavities.
Also, there can be NO sanding done after the planing. So you need to have sharp knives in a finishing planer going slow. A cleanly planed surface is much nicer than a sanded one anyway . . .
All the cavities were freehanded with black stain.
The Headstock backplate was sealed around the edges, then freehanded.
The back of the body was brushed with multiple coats of stain and then rubbed out with 0000 steel wool to burnish the finish.
All black surfaces were rubbed with the 0000 steel wool to burnish the stain and get a softer, "glow" sheen that is really only apparent in real life.
Then, the whole thing was shot with satin polyurethane (cept for the fingerboard of course).
A note on the color motif for anyone who may not have made the connection: the back of the guitar is a black/woodneck/black motif, while the front of the guitar is the opposite: wood/blackneck/wood motif. Most people would catch that, but just in case . . .
Also, this bass has solidified one more thing for all my future basses: I will use the Fender style nut/fingerboard overrun at the headstock. I much prefer it for a lot of reasons, all of them to do with "ease" and I like the finished look much better.
