Customizable flat field box

Simple flat field box particularly suited for small lenses/telescopes, but highly customizable.
SCAD sources are included, just change values in `flatbox-config.scad` and then open and generate the appropriate file (you can also use the included `Makefile`).
Required parts (apart from printed ones):
- white acrylic/perspex round panels. Be careful to choose the white version, NOT tranparent.
- white leds. I recommend adhesive led strips, so they can be attached without glue
- wires: ver