Reply by crank49

Torsion box, wheather the core is a wood grid or foam, is the way to go.
Sinse the skins are in compression or tension only, you can use 3/16 hardboard and be plenty rigid.
If you go with foam, I’d use the thickest practical, 2” perhaps.
Also, with foam, be sure to use an adhesive designed for foam. It’s readily available.
I would make a perimiter frame out of wood even with the foam core to protect the edges.

And, I agree with others here, keep the tiles as thin and light as possible.

-- Michael :-{| Diapers and politicians both need to be changed often; and for the same reason.