A handmade voronoid-like pattern designed with dualstrusion in mind... however, the example box(es) here have been made for single extrusion :)
I did tried my infamous combination bird-pattern with this (you can see it hiding rear the yellow box in one of the pictures) but... still needs some work before I can (?) upload it.
The thing here is "gPattern.scad" (I call it "g" for giraffe) it has 3 usable modules: one to draw the lines, the other to draw the spots and a third one to display some "help" (parameters name and default values).
The ZIP file contains boxes which side length ranges from 25mm to 125mm in 25mm increments. The two versions are available (spots and lines).
I did find some issues, please find the details in the instructions.
Download the ZIP, pick the STL you like, slice it and print.
The pattern compiles fine (unless you combine it with something else, which normally should be the case) but takes some time to render. The boxes don't render fine and take up to 15 min.* to compile (* - I use a 4x2core laptop with 8Gb RAM powered with Linux)
Scaling this thing... keep in mind that there's a 1mm thick wall.
The "spots" versions suffer from "Dangling Edges" (ouch!!) I found no issues printing the 25mm and the 50mm versions but.. check out the picture from the 125mm one to see what you risk if you give them a try (I should try to repair them...).
The "lines" versions printed fine all of them (did not try the 125mm but I see no reason why it should not work)
I first tried a purple in ABS which curled, cracked and melted with the platform (it was very difficult to put out).
Then I tried few randon boxes using PLA as material with the middle wall set to 0.6mm. They printed fine (but for the orange/pink/whatever one which coil was not wanting to unwind).
The STL available here have been generated with the same values for all the parameters but the side length and the thickness of the lines for the pattern, this is: 2.5mm for the total thickness of the walls and 1mm for the thickness of the middle wall.