Tonycardall wrote: I may even venture into metal vehicle/loco kits once this project is over.
Well, improving skills and building confidence is what this is all about - so very well done!
I did mean to comment about the process of joining frame units. I see from your photo that a number of the frame sides do not line up:-
Don't beat yourself up about this - it is a feature of the etching technology but it is important to do something about this because it means that the spacing of the tray sides will not be consistent along their lengths and this will create inexplicably tight or slack locks.
The best way to treat the problem is to make up a little gauge, a shade under 5mm wide and also a short straight edge 55mm long (something like 30 thou plasticard is fine for both) and use these to tweak the tray sides with smooth jaw pliers to be straight and the correct spacing.
The other thing is that, at the time of assembly, it is worth very carefully, taking the sheet curl out after the tray sides are bent up and before they are soldered - again using your 55mm straight edge. The same is true BTW for the tappets - take the curl out before soldering.
Sheet curl and local over/under etching are unnaviodable and managing them is not a problem once we are all aware of it!
Just to say, please don't think for one second that I am criticising what you achieved with your first attempt - far from it - I would have to be honest and say that in the rush to get on, I have done a fair few a lot further from perfect than yours - and I can't use inexperience as an excuse
Also, I see that you have succeeded in using 0.8mm wire for your cap bars - well done for that - but you might find that on long bridles, they can make the lock stiff. Be aware of that and if you need to use - say - 0.7 or 0.6mm dia wire to ease things then no one will critcize and it will be no detriment to the job. And you certinaly do not need to fit every single one - as you will notice from my photo.