What is involved in making this?

[the great waldo]

Finally a question related to my job. As a guitar maker I would recommend that you cut that out of a piece of steel 1.5 mm should be thick enough with a fine tooth piercing saw. For a one off it is overkill to do it on a cnc. It would take about 30 mins to cut that out. I would make sure that the edges especially underneath are rounded over as screwing the neck down can put enough bend in the plate to crush the laquer. Most of those basses were ash which was quite hard but if you have an alder one it's a lot softer. I checked out the prices on the web and the parts dealers are taking the piss with the prices they are asking. Good luck.
Cheers
Andrew