Having fun here.
Here, the frame that joins the two tracks is being built. I filled the center frame with foam slabs and put a styrene plate in the bottom and on top, with a tube joining them. The upper section of the crane will pivot in that tube.
I also added a reinforcement plate to the inside of the track frames. It needed to be wider as well as stronger. I can't get to my styrene stock in storage, so I used a handy bamboo skewer as the shaft for the upper crane body to pivot on.
