Thanks Gents, these have gone on Ebay as they are a bit big to store. I'm going to make some individual ones so I can have different configurations.
With regard to the bricks, they are made from DAS clay.
I made jigs using plastic card bricks and used DAS to make an imprint mould. The once dry I use more DAS in the to make small sheets of bricks and then glue them to foamcore.
cheers
Geoff