Thanks Petar for those few kind words, I find them very encouraging.
It's one thing to work on the computer and produce nice drawings, or even to print it and cut out a card mock up, but it's a very different thing to work with the actual metal, etc., of the model.
Since I'm using brass, I plan to solder it together, and apart from plumbing I haven't done any of that for many years (like since I was an apprentice engineer
The main problem I forsee is in accurately securing the various components in a position where they can be soldered without disturbing them. The answer I think lies in making a jig, e.g. for one corner of the frame, which can then be used for the other three corners.
Mention was made, I think, of you asking for some help, I'll be very pleased to come over sometimes, either an evening or some daytimes.