Was it possible to get some form of restitution from the original metal suppliers ? The thought of them delivering a production run of vastly lower quality than the sample is appalling. I mean, why even bother with getting a sample made, if they are entitled to provide whatever quality they like at delivery ?
It sounds as though you kept that metal and built them up as "B Stock", but I hope the metal house at least gave you a substantial discount - I'm guessing these chassis were used as there was no "return for full refund" forthcoming ...
Edit: In fact, I'm guessing the idea of "return for full refund" is so alien to the inter-manufacturer dynamic, that you might still be laughing at the naively of this consumer.