After the embarrassment of my Isle of Man Test track Mk1 turning into something more akin to a roller coaster, we've made a second version which is currently with the sanding and finishing department.
The materials remain the same - plywood top with softwood framing - but without the fancy corners from the first attempt that I feel might have caused some of the problems. The corner blocks that keep the boars apart in transit have been fixed to the ply tops with thin ply slabs on the side to brace them. Easier to do and just as effective as my joinery attempts. We've varnished the wood very early on in the process too. If there is any moisture in there, it's staying put this time.
So far, things are looking fine. After the next coat of varnish dries I'll be screwing the metalwork in place. Then it goes off for the track to be laid followed by some wires and perhaps even a bit of scenery.