i've made many controls panels over the years, but my latest one was the first one i did artwork for. i saw many examples of people with awesome graphics surrounding their controls, but i know that if i was off but a just a little, it would drive me nuts seeing it off center. so i opted for artwork that filled the panel, but didn't require pinpoint precision. The shape of my panel was pretty basic, so I took some measurements and made a full size (46"x18") 300dpi photoshop file. I laid it out with guides and used button/joystick/trackball images that were sized to the proper scale to lay out my buttons on the panel in photoshop, then just removed those layers before printing it. (I actually made the image an inch larger than the panel in both directions so i had 1/2" of bleed area around the edges.
as for the drilling/cutting. i went old fashioned and used a ruler, square, pencil and compass to mark out of the holes and drilled them, i didn't use any paper templates. once the holes were cut in the wood and plexiglass, i placed a bright light inside the control panel box so the hole locations were visible through the graphic overlay. i lined it up the paper overlay, cut out the holes with an xacto knife, then placed the plexi on top, inserted a few pushbuttons to hold everything in place, then trimmed around the outside.