A base design to change, evolve and see where it leads
This is a print-in place box, yet to be decorated with the necessary features to connect the sides. There are dozens of design choices, directions to take with this one.
First, this is a quick mock-up in OpenSCAD - doing the same in FreeCAD would take too much time and effort.
Next, the features connecting the five sides maybe printed in different Z heights. When printed in PLA, and kept to the minimum height (0.2 mm), they remain flexible. When printed in PLA with 0.6 mm or higher they can be bent in place (right-angle or wider) and once the PLA cools they stay in place.
The primary purpose with this design is to print boxes with different configuration for X, Y and Z. For each the sweet spot for stabilizing the plains must be found in the thickness of the plane and the stabilizing rim. Most likely the sides and the bottom going to end up with a different thickness, rims, and the OpenSCAD model going to have some repeated scripts to make that possible.
There is an option to open the one side and connect two, or open two sides and connect more to build bigger boxes, larger than what can be printed in a single pass.