You should be sorry for asking about panel planning. Ha ha.
1) hanger flying is a tool for overall layout. I would not covert it directly even if you could. Doubt you can. I find scale is slightly off but still good for rough layout.
2) You will need to get the cut out and fastener pattern dimensions for you avionics, instruments, switches.... or measure directly. Leave a little room for paint.
3) I suggest cutting cardboard patterns size of BEZEL (different than cutout). You can print scaled pics and paste on the cardboard.
4) Structure behind panel. I can speak to RV7 slider. There are 2 side and 3 top stiffeners, and bulkhead about 8.5 inches fwd.
5) Two choices in layout:
A) Use pencil and paper and draft it out, not hard to do. Must dimension, accurately, if someone will use to cut panel.
B) Download DXF file of panel from Van's Website, open with free 2D CAD program (I use LibreCAD). Go nuts putting shapes (to scale) on panel.
6) Cut panel two ways:
A) By hand, drill, hacksaw blade, jigsaw, Dremel cutoff wheel, files, punches (made for 2.25" or 3.125: round instruments). *
B) Bring panel to machine or metal shop to CNC or Waterjet cut. They will use your DXF file and convert to tool movement.**
I would not cut squat until you have bought all or most of the items going into the panel, not what you dream of, but what you have and will use. It is OK to cut extra hole/cutout for future item. I did that on co-pilot side. I likely never will add a second EFIS but it will make a great access panel. What you think will fit might not due to depth and actual envelope behind the panel. You may decide to not go with one brand of avionics or instrument and switch. On the other hand don't buy avionics too early, as they evolve fairly quickly and what is new today may be outdate in a few years from now. Like PC's I think the evolution has slowed slightly. Consider remote COM, TXPDR. Most EFIS can be control head for those, as well as NAV (VOR/LOC/GS). I went with a panel mounted COM just because I felt it gave me some redundancy. Advantage of remote boxes is it frees up panel space, and there is no need to cut the panel bonus.
** Most shops that do CNC or waterjet, will do all the CAD layout from your paper pencil sketch, for extra charge. Special shops that cut RV airplane panels can lay it out from your Hanger flying design just by looking at. They know the stay out areas and typical or best practices. It should be a piece of cake for them, may be 1-2 hours of labor. However they will do what you say, so be sure. You still have to design the layout. They may advise to change things. Consider cutting a piece of scrap plexiglass or other suitable material first before the metal panel. Check it. You DO NOT have to go to aircraft panel cutting place. Any metal shop with CNC or Waterjet can do it. Just make sure you check it carefully before cutting. Again structure behind panel is a function instrument / avionics depth and position on panel. Van's does have a 3D CAD model that would be better for clearances, but 3D CAD software has higher learning curve. There is free 3D CAD software. EAA offers free 3D CAD software to members or use to.... I am not sure if it is a full version or limited. For a flat instrument panel 2D is good enough.
* OLD fashion way is not too bad, machinist scale, scribe, center punch to do layout right on panel.... Small holes in corners of square/rectangular cutouts to get cutting blade started works...... You have many ways to cut, scroll saw, jigsaw, cutoff wheel, hacksaw blade with handle on one end. Then file to final size. Holes a drills, fly-cutter, instrument punches (often you can borrow from EAA Chapter, local avionics shop will do it, for little to no charge). Prime and paint panel. Get some transfer decals to label switches. Clear coat, mount the goodies, done. Should look professional. Their are shops that DO IT ALL.... and it will not be cheap...
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Not actual layout only practice for example. Download blank DXF CAD panel from Van's. Note Vans CAD panel shows bottom flange flat, subtract for layout (RV-7 Slider)
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Modified Van's file showing actual panel height of my panel. There is going to be tolerances at the bottom bend radius for flange, +/- 0.05?
FUN FACT: The instrument panel does NOT go to the 51% builder rule. Just saying, does not count. Seems strange but true.