This is for Tom who asked here how the vertical beams connect to the horizontal ones at the corners. The answer is that it is a mortice and tennon joint which goes right through and also holds the two corner pieces together. Very neat!
The two corner pieces are joined by a special kind of dovetail joint which has a very long name in German and Hannes didn't know if it had an English name. He described this joint as a mixture of French and German techniques and the whole building uses a blend of various different European joints. I think that cutting these joints will require a great deal of patience and accuracy and I am really looking forwards to seeing it happen.
(Again this was communicated via the wonders of Skype with Hannes sketching and holding bit of paper up to the camera to explain!)