1/4" x 1-3/8" x 14' lattice stock, 1/2" plywood and 1" x 4", rough cookie cut, trim with router, lots of polyurethane glue and spring clamps, cork painted grey, Atlas code 83 flex track and switches, RTV adhesive/sealant and some solder, limit switch on the switch machine to energize the proper siding.
 

Oh, the weight of the trapezoid and all the stuff in it holds up the loop and the train!