We have the 'final' part of the first 'print and play' building. I say final, I've suddenly realised I can make some more sizes. 2 window section widths would allow you to make a tower, add in a Modular Plug and cut and rebate the socket on the roof and you could add extra dimensions to these simple structures. Alternatively it could be slotted into a CD base. However, I'll start releasing my second building skins before I go back and create a new size.
Essentially all you really need to do is print these, stick them to foamboard and cut out. I might suggest using A4 sticky labels for the printing, then either bevel the edges to 45 degrees or remove an interior 5mm strip so the boards can slot into each corner - simple!
To access the full STC please point your Cogitators here, be fair warned it is 42MB in size [I make no apologies for this, I could probably render it as a .jpg but what the hey?!]:
Alternatively if you want to reduce the footprint a bit and still retain some of the proportions you could employ the standard 2 storey template on one facing to make a rectangular building instead of a square one. It's your choice but here's another 'artists' rendering and a link to the page where it's at.