I needed a simple box for holding a breadboard up top, and some relays / a power converter / whatever underneath.

I've never used OpenSCAD before, but you should be able to set your breadboard size (for full, half, whatever) as long as you can measure it (include a couple of mm for the nubbins on the edge). You can also set the amount of space under and over the board.

I'm working on a lid for it, will be in v2!