extruded foam

On the original SPL I tried out riveted galv-steel wall framing with 50mm blue extruded Styrofoam glued to it. I got frustrated by the difficulty attaching Tortoises etc to the underside of the foam, and of getting a durable hole through it to operate turnouts. Next time I would laminate a thin layer of plywoood or at least MDF under the foam. this would also allow cutting into the roadbed for creeks and underpasses without undermining the structural strength.

Also i found the 50mm (2") thickness complicated Tortoise installation. I am enjoying reverting to 12mm ply roadbed on the latest layout.

i laid cork on the foam, and glued the cork and track with latex caulk not PVA [USA: "white glue"], and it wasn't too noisy but I made no comparative measurements against other techniques.

But it sure cuts fast and easy, and lifts and transports effortlessly.