(Click on the above thumbnail picture to see a larger image.)
The tricycle's structure is constructed from polypropylene (a thermoplastic polymer). The polypropylene is cut with a CNC router, before being folded and welded into shape, retaining its strength but gaining a certain degree of flexibility. This allows the Tricycle House to open like an accordion, and offer modern amenities like a bath, bed, and water tank. It can even attach to other Tricycle Houses to increase available space. And, yes, there's even a bathtub/shower. However, I don't see a flush toilet in any of the pictures.
Further details are available at http://goo.gl/iXrvz.