I just dropped this on Printables: A FreeCAD based custom size box generator. I've been using it for all kinds of stuff. Maybe some of you lot will get some use out of it, too.
https://www.printables.com/model/770701-parametric-simple-custom-box-maker-freecad-generat
Plug in your parameters, make a box with filament hinges -- No hardware required. No screws, no nuts, no supports, no glue, no Fusion, no proprietary software, no going cross-eyed looking at OpenSCAD code.
(And yes, the default size in the file will make an M:tG card deck case.)
Cool. Hope to print one later. Last week I have been searching for exactly this and could not find it. Did you think about an option for adding some simple dividers inside the box?
I'm sure there will inevitably be innumerable variants. I was thinking of adding a generator for Gridfinity inserts, and dividers wouldn't be too tough to add, either. Or handles, or swivel latches, etc., etc.