:D All signature prototypes are hand made. This includes guitars, P/U`s, Fx pedals all of it. It`s not tenable for the manufacturer to make something designed by the artist so they can endorse it with a machine. It would cost to much.
Once it`s been agreed with the artist it can go into mass production. Yes Vai, Satch,Johnson & Timmons all have hand wound pickups as for scatterwinding......?
:D 8)