In order to accomodate the Stanier 8F loco and tender that I'm using instead of a BR 57, the loco and tender have had to be adjusted to acommodate the additional length and different wheel positions. I've tried to keep the overall as close as possible, with the armour panel edges at midpoints between axles and the access hatches on the loco centred on the driving wheels.

At the top is the original model, below is the extended version to fit the 8F.



And here are the unfolded versions ready to print.



Finally a shot of the half train model with the extended loco: