The frame is built out of gavanised steel tube with the main supports for the base being 100x50x3mm.
General framing for the walls, storage compartments, roof etc. was created out of 50x50x1.6 mm.

The base was created, carried into place then flipped onto the chassis. 
Once the base was attached to the chassis, the wheel arches were created and cross members welded in to support the ply floor. 
The combination of a flat floor and a stepped chassis meant there was quite a bit of space created under the floor and between the chassis rails.
For roll-over protection, a pair of 50x50x3mm galvanised SHS frames were placed just behind the cab. 
These were clamped into placed then welded to the chassis. 
The walls and roof were added with a recess created for the roll out awning to reduce the likelihood of it being ripped off by a tree. 
The roof frame completed ..  
The first layer of plywood flooring added .. There are now two layers of ply flooring seperated by air cell insulation. 
Wall framing mostly completed. The window frames are done and the framing for the bathroom has been completed.

Some of the 3mm aluminium chequer plate cladding has been attached.  
The bathroom taking shape - the floor is raised so that a 180 litre water tank fits under it.