If you haven't cut the holes in your control panel yet, you could alway do what I did:
I measured the buttons and joystick's holes and did a blank template of my CP in Photoshop, by creating a wire frame the size of my control panel and adding wire circles for the buttons and joysticks.
You will need to have 2 embedded circles for each buttons/joystick. One circle will represent the outer edge of the buttons(or joystick cover) where you know you will be able to align text near the buttons/joystick and the other one will represent the size of the hole you need to cut.
Thereafter you can print the empty template on regular paper (altho you will probably need to tape two sheet together to recreate the size of the CP), and tape it to the plexi and/or wood to use as the template for drilling the holes.
When you are ready to create your CP's artworks, just redraw in your photoshop template knowing that all the holes will be at the exact same place.
I even have my printed template under my plexi until I finish doing the real artwork.

Mine looks something like this:
When Making a control panel overlay how do you make sure you have the right size, buttons are in the right place, and all of that kind of stuff..? Is it just simple trial and error with measuring things or what. I would really like to make myself a CP overlay but Im not real sure how to get started. Thanks Brad