Fender neck on a Gibson set neck body

[dave.king1]

I have used overlaid masking tape to create a pattern for shaping wooden cover plates. You lay it over the void, run a fingernail or a skewer around the edges to mark them and then remove and trim to those marked edges. Lay that over your plug blank and cut to rough size, then test fit and sand to final size.

That's how we used to make gaskets back in the day, and still do on occasion

[FrankenWashie]

That's how we used to make gaskets back in the day, and still do on occasion

My older workshop tech still uses that method for odd size pump flange gaskets. Lay the sheet over the flange and gentle taps with the ball end of a ball peen hammer.

[Sonic Mountain]

Same, that's how I was shown to do it as a mechanics apprentice back when dinosaurs still roamed.