Way back in the late 1970s, I was trying to find decent trees to populate a diorama I was building. It became clear that to get an acceptable tree it would require some work. Somewhere is dusty pages of Model Railroader, I found that some intrepid modeler had made trees with some wire and plaster.
I tried to duplicate the idea using some plated wire I had left over from an electronics build. The wire was twisted into a bundle and soldered together to create trunk and upper main branches. The finer ends were fanned out to create the tree’s structure. The armature was cleaned and them coated with Durham’s Wood Putty. The stuff dries rock-hard and can be textured as it nears the hardened state. I painted the trunk with Floquil brown, black and gray. The leaf structure came from Woodland Scenics.
I gave the trees to Bob Brown and may still be on his layout.