It's slow progress, but just to show I have made some, here's photos of the new fiddle yard under construction. The rather complex design has led to some head-scratching, and a lot of time has been spent marking out and cutting the pieces, but it is now starting to come together.
The frame is 9mm ply (left over from my son's train-set board) forming the back and ends, though due to depth limitations the lower level is softwood.
The deck layers use a foamed PVC material (Palight is the brand name) which came as offcuts from the marketing department at work. It's reasonably strong - as good as ply or MDF of similar thickness, and possibly lighter - while being smooth faced and of course shouldn't warp if it gets damp. And it was free! Small section (10x18mm) timber strips reinforce the edges.
The drawer runners that Awngate used to be mounted on have been fitted to timber cross members. Their travel isn't long enough to allow the deck to slide out to clear for rotation, so they have been mounted in pairs to work together for double the travel. I'm not sure if that will mean too much slack.