It is designed to be modular and a bit different to a slab sided lorry back. The two modules are designed to look similar and tie in with the look of the old crow style. I have tried to make these look less slab sided by sloping all four corners inwards whilst retaining vertical surfaces where the irises and end windows are.
This allows the modules to be removed from the chassis and grouped together (iris to iris or window to window) to make temporary camp structures such as this.
I can imagine this being a mobile hospital, a command HQ, a temporary laboratory or any number of other uses. If nothing else its either an objective in a scenario or some cover in a fire fight. This should allow quite a range of modular temporary structures to be created. Whilst each of these modules is a little small, they are completely mobile.
I think I shall modify the plates on the roofs so that they are all the same size and interchangeable, that way I can scribe one side with symbols such as red crosses, arrows and biohazard symbols. Then the buildings can be assembled either plain or with symbols showing - allowing the buildings to have multiple uses. Likewise I can make the Iris inserts double sided so that they can show open/closed Irises or blanked off walls.
My only regrets are that I haven't figured out how to make good double height structures without having slab-like vertical 'boxes'.
EDIT 21.01.10: Adjusted the module on the truck back to allow this:
As to sizes, the width of these modules is 46mm not huge but thats the width of the chassis. The larger modules are 92mm long to match the length of the trailer chassis.