I've had my screw-box printed at the campus. and it works perfectly.
tip: the easiest way of getting the box close with the pencils inside is to put the pens in the black one (screwbox_single_side.stl) and then to screw the white (Screwboxvariation1-1.stl) one on it.
The parts I used for my pencils are(scaled to fit the up):
Nozzle size; 0.4
Layer thinkness 0.2
Material: black and white ABS