I wanted a low sided gondola to go with my Bobber Caboose (http://www.thingiverse.com/thing:1363887). I had found the excellent G-scale Flat car by pmo (http://www.thingiverse.com/thing:183820) that suited my needs.So I've downsized it, redesigned the bogies and added slatted sides and new stakes.
The model can be printed to make a flat car, a flat car with stakes or a gondola.
I've used LGB knuckle couplers but they're a bit oversized and I'll try to design smaller ones later. You can also use standard LGB couplers.
0.1 mm for small parts and 0.2 mm for the bigger ones
As usual, I've printed everything with ABS.
The only thing I printed with support is the Truck beam (I'm not even sure it's really necessary but I didn't try without).
The Frame and the Body are printed with 0.2 mm layer height, all the rest with 0.1 mm.
The Brake wheel rod is Made with a piece of 1.75 mm filament.
Insert the 2 mm washer between the truck assembly and the frame when you bolt it.
Glue the 3 pieces of the frame and the 3 pieces of the body on a flat surface. Insert a 3 mm nut in the 2 hexagonal slots on the frame. Then glue the frame to the bottom of the Body. Glue the 4 truss rods to the frame.
The 3 pieces of the bogie are glued together. As axle I used 3 mm steel rods.