Update 25. Jun. 2021: fixed bug with only the sides rounded; this is also default for better printing

Description:

This is a parametric rectangular, waterproof housing made with openscad.
There are two files: housing.scad is the module which contains the logic and housing_example.scad is the file with the parameters.
Included is also an example file in stl format with an inner size of 75 x 130 x 25 mm. The images included are made from a modified version with already holes and a dovetail joint (https://www.thingiverse.com/thing:3148124).
To be waterproof, there must be a gasket in form of a rubber ring, which can be found in office supply stores. For the example the rubber ring should have a 1.5mm thickness and 396mm total length (better choose a little shorter).
You need 4 water resistant screws 3.0mm x 16mm for the example.

Printing information:

Open the housing_example.scad in openscad. Important: preview doesn't show everything correct due to the complex structure. Press F6 in openscad to render it. The variable names should be rather self-explanatory. The inner size does not include the screw sockets, so the available volume is a bit smaller. The dimensions of the rubber gasket are printed in the console output of openscad. The tolerances and gaps should be fine for a calibrated printer. You can switch on and off the bottom/top part and choose the arrangement of both: side: next to each other, fit: closed, demo: above each other, overlap: both in origin.

Slicer settings:

This is not very complicated to print, but the big surface might make the bed adhesion at the corners problematic. I was using ASA as material and Cura as slicer and these settings (beside my standard profile):

build plate adhesion type: brim
wall line count: 8
top/bottom thickness: 0.8
bottom thickness: 0.8
infill density: 100%
optimize wall printing order: yes

Additional Information:

• ASA is sturdier than PLA and UV-Proof for outdoor use, but more difficult to print.
• Don't tighten the screws too much; the groove between top and bottom part should be constant along the sides.
• No guarantee on the waterproof performance! The area around the groove for the rubber should be perfect.
• Use clothes pegs for fiddling in the rubber ring