The 4mm scale MDLR had a couple of delightful freelance sheep wagons, built from kits by Colin Ashby. I've at last got around to producing something similar, but four times bigger!
Axleboxes, wheels and couplings came from Imp Models and the corner "angle iron" and hinges for the ramps from P&J Models, via
PPS Steam Models.
All the rest was stripwood from my local model shop - I was surprised by how much was actually needed!
Eventually, I gave in and painted them.................
.............. but they do look quite nice! The sheep have been stuck down, after they showed a distressing desire to fall over and thereby derail the wagons.