The foam-core baseboard is nice and light but vulnerable to knocks, so really benefits from being clad in a robust material such as plywood. I had an off-cut of 4mm ply in the garage, so spent an evening marking it out. The shapes are quite complex, as well as the board being triangular the ply forms the scenery fascia, has openings for access and the control panel, and of course the back panel forms the backscene.
Another evening was spent beating the ply into shape! The sides are simply glued to the board, but the backscene being curved was somewhat more complicated. I poured boiling water over the part to be curved, which helped a little I think, but while 4mm ply is happy to warp into all sorts of curved surfaces getting it to bend a little was surprisingly difficult!
With the help of a lot of PVA glue, some screws, and some big clamps, it all came together. It may not be quite square and a bit rough in places, but I'm pretty pleased. Plus even now it only weighs 150g!