Customizable interconnecting slotted mini-crates

I needed battery holders and everything I saw had a fixed design, so you could not easily add support for a different size of battery or some other object.

This is an attempt to make a generically-sized interconnecting storage box with multiple sections for arbitrary round or rectangular objects.

In the customiser, if you specify the diameter of a round item, it creates round slots. If you specify 0 for diameter and instead specify item dimensions, you will get rectangular slots. If you