Let’s start with the printing first. You can assemble the electronics (on the next page) while the printer runs the job.
There are three parts (each in a separate .STL file): the case front and back, plus a thin separator that keeps the filter from pressing into the fan blades.
The case front and back measure 84 by 53 millimeters, while the separator is 50 mm square. For tiny printers like the M3D or Printrbot Play, print each piece as a separate job.
“Normal” quality (0.2mm layer height), 25% infill works well. Both PLA or ABS are fine, in whatever color makes you happy. With a light or transparent color, the PowerBoost status LEDs show through.