Hello John,
Although there are no instructions, I use the original parts for the frame, cutting them out and glueing them to the laser-parts. these are really accurate, and I trim the original parts to fit the laser-cuts when necessary.
All those parts are indicated they should be re-enforced
The parts for the wheels are replaced by laser-parts .
It's not necessary to double up the formers for the inside of boiler
I'm specially pleased with the nuts from Avant-card,
AvantCard - Home ,they save me a lot of boring work, actually I think it is strange they are not included in the laser-cut parts