I take issue with calling the Volvo C303 a knockoff - it is an original design from 1974 for the Swedish military. (Most of the civilian ones you see today still have the roof hatch for the gunner!)

Regarding building codes: The staircase is in Sweden, where it is legal to build a staircase, and other things, in any way you want inside your own house. (There are regulations about fireplaces and elctricity, but that is about it. And public buildings have accessability codes.)

I like the homage to the wunderful novel "Flatland: A Romance of Many Dimensions" from 1884! Especially when the hero has his own little flatland to study in his office. Read the book, it still has a lot to say about both dimensions and society! The author is Edwin A. Abbot, and it still available on Amazon (as a reprint).