I never made them, they came that way. Masking was mostly either tape or they just milled out the lettering after painting. All I ever did was fix up chips, and used a can of satin black paint ( looked better than the matt black paint) and simply gave the whole panel a coat or two, then used a scriber to remove the paint in the lettering along with a masking tape applied to the edges where light was desired. the lamps were 5V grain of wheat lamps (or some had a mix of both 5v and 28V lamps in places with 2 supplies) that were soldered into channels in the back, with the leads connected to wires and solder points that were in milled and filled slots along the panel. Not cheap panels to make, but they were aircraft cockpit panels and had to be durable and dimmable.