I've already shown pictures of my 3d-printed SP CS-35A flat cars. I've also hinted at my F-50-4 models - 1915-era flat cars with very thin decks. I've printed some of those flat cars; they're visible on the video that went along with the CS-35A article, but they're also a pain to decal because the prototype lettering looked an unreadable four inches high. I'm feeling pretty good about both these models, and happy to be on my way to having some flat cars for lumber service on the Vasona Branch.
So what's next? Looks like it's going to be the patented Hart Convertible gondolas, known to the Southern Pacific bean counters as the G-50-4. Harry Hart of the Rogers Ballast Car Company designed a gondola that could be used for different jobs repairing a railroad's maintenance-of-way. Doors on the side of the car open to dump fill dirt out. The floor hinges up to open a hopper area to dump ballast between the rails. The end bulkheads could be moved towards the center of the car to keep ballast near the hopper, or removed so that rail or other heavy material could be dragged off the end of the car. SP had around 700 of these cars, which existed into the 1940's.
This has been a pain to print. It's a forty-foot car, so it won't print flat on the Form One. Printing the model tipped up allowed the model to print, but the support material to hold the half-printed car used a ton of resin. I also had problems with dirty mirrors over a few weeks that resulted in several failed attempts and a lot of wasted resin. But after finally identifying the problem and cleaning the mirrors, I've been much happier. I've found that I can print the cars vertically with pretty good success. Those successes also mean that it's possible to print 50 foot HO freight cars on the Form One.
And the detail's mighty sweet, too - the castings for holding the door print cleanly, as do the underbody trusses and hopper assembly.
I'll tell more later - I'm still working on this. I've just finished a second print of this model with correct strapping for the hinged doors, hinged metal apron to cover the spaces between cars, room for the brake wheel on a corner, and a mount on the side of the car for the brake cylinder. However, this photo at proves that I'm actually printing non-trivial 40 foot cars.