For my next project rather than design and drill the panel then print it to fit, I will design the panel layout in FreeCad and produce a design that can be 3D printed so that it can be used as an erognomic test print and drilling template, once that has been tweaked, a template can be printed that is dimensionally correct for all the holes and slots that might need drilling in the metal case.
That dimensional design can iterate to be the basis of the new front panel.
The dimensional design can be kept as a computer file so that it can be used if a panel redesign is needed at some time in the future.
I had this idea when considering use of a software implemented s-meter.
As a service to fellow home constructors out there - I might look at offering to print your STL files from your panel designs if you fund the print and return postage.
I will look at the realistic dimensions from my printer bed that can be produced accurately.
Let me know if you are interested!