Charlie Vlk wrote: "'Back in the day' of early Japanese brass supposedly a model was built with a fold line from the reference blueprint faithfully rendered on the side of the model."
We don't even need to go back that far - how about the first run of the HO scale Atlas offset twin hopper cars with the doubled center side post resulting from a bad drawing splice?
At least they still can be used as fodder for the Sunshine Alternate Standard mini-kit!
