Step 3: Designing a template
I just sketched a template for the panel out on paper to start with. You can arrange things however you like on the board, depending on the size of the case you are putting everything in. I designed everything on a 8.5"x11" piece of paper and just centered it on the wood panel (12"x12") when it was time to start cutting.
Start with arranging the speaker terminals, which I put on top in two rows of three. They have an outside dimension of 2-3/4" x 15/16".
Next came the toggle switch, key switch, and fuse holder. I centered the toggle switch horizontally on the board right under the speaker terminals. The key switch is to the right of the toggle switch, and the fuse holder is to the right of the key switch.
Underneath these main switches are the pushbutton switches and LED status indicators.
The buttons I arranged in 4 columns of 3 buttons. Each button also has two LEDs; one on either side. I did not include the LEDs on the template, because I just eyeballed where to put them. You also might want to arrange them differently on yours, by putting the LED pairs under the switch or above them instead of on opposite sides.
Attached is a PDF template so you can print it out yourself. Print it and tape it over the panel you choose to use, and you can drill/saw through it to get everything properly lined up if you want to match my layout.