Apologies for the late reply!
The basic construction principle is as follows:
a) I use 3D-printed stand-offs that exactly match the inner geometry of the Peli cases. They contain a M3 thread, which I manually cut into the printed parts (cutting threads into PLA material works pretty well).
b) The panel is made by https://www.schaeffer-ag.de/en/. Since their service is not exactly cheap, I start with 3D-printed prototypes until everything works and looks as needed. You can design the front-panels with the free tool that Schaeffer provides:
However, what I do is export the cutouts from the 3D design and import them into their tool. I only use their tool for fine-tuning, like the countersinks.
The text and drawings are created in a graphics program and imported as an image into the Schaeffer tool. This is less work than using engravings, gives you more freedom in terms of design, and is multi-color.
All the materials will eventually be put up on GitHub, but I will need some time to finalize this.
Main Project and 3D-printable parts: https://github.com/mfhepp/gobox
DC-DC Boost Converter: https://github.com/mfhepp/gobox-power
TinySWR Indicator: https://github.com/mfhepp/tinyswr
Audio Amplifier and Zero Beat Indicators: https://github.com/mfhepp/gobox-audio (currently a mere stub)
For your own project, you will likely only need
a) the stand-offs from https://github.com/mfhepp/gobox/tree/master/standoffs
b) the front-panel from https://github.com/mfhepp/gobox/tree/master/frontpanel
Hope that helps!
73 de Martin, DK3IT