I’ve been in a “3D sketching” mood lately, so why not?

This is very small (~2.8×2.8m), and not even “furnished”… I have some ideas for an even smaller one.

I like the “bottom” slit for the door, but I have to figure out a hatch design that works for it… maybe something that slides up and down with some kind of extension rod: guards shouldn’t have to bend over to open it.