The trouble with building a batch is that when you make a mistake, you replicate the mistake for each member of the batch. So, despite passing Saturday morning enjoyably melting tiny pieces of plastic strip into globs that look passably like body bolsters, I now have three flat cars that all sit approximately .030″ (.75mm) too high.
Some analysis with the drawing and a pair of calipers traced the error to several mis-measurements and mis-calculations, each contributing a small amount. Together the small errors add up to a clutch of models that tiptoe on the rails like ballerinas, rather than hunkering in their boots like the lumberjacks they are meant to be.
It’s too bad, because not only do the iron body bolsters look cool, they are also now incorporated into the brakes. Fixing this is going to take some thought.