Hmm, I replied to this thread yesterday but... it's gone?

All your points are taken on board, thank you. I've been in contact with John S with interesting results.

Jonathan, I would far prefer to buy at once as well. For a number of reasons that is not feasible in the short term so the "buy a little often" approach is much more likely to lead to a completed project! I'm hoping that by the time I have a decent solid frame in place, I'll be in a position to start making those big purchases.

The Alu Profile site is bookmarked and very well browsed!

I'd welcome any thoughts on the 40x40-based design thread as I prefer to be able to have the design in place before buying anything.