IMO, figure out the hardware first. Once you know what you are going to have in the panel...order it. When you have it in hand, find some cardboard and build a test panel. Configure it to work (wiring doesn't have to be pretty yet, this is just for testing). Play around and decide on what improvements are needed. You will likely go through a few iterations, but cardboard is cheap. After you have something that physically works for you, make the artwork and, if you want, add the controls to the art (this will help later but isn't required). Send it off to a printer (there are a few on this site) and wait. Cut wood, add overlay, install controls, have fun!