This is a little enclosure for a standard 16x2 character LCD (NewHaven Display in the pictures) to mount it to an Adafruit Huzzah breakout. I currently use this to sit atop my Open Energy Monitor EmonTx v3 to display power usage and upload it to EmonCMS.
The "wall" thickness might need to be modified depending on your extrusion width and perimeters but the interior volume will stay the same.
The screws are M2.5. I used 14mm because that is what I had on hand, but the center Huzzah mount screws will need to be shorter. I just cut the M2.5x14mm to length.
It is just a calibration cube with a hole in it! I print it at 0.24mm layer height with 2 bottom and 3 top layers, 2 perimeters.