John, that sounds like exactly what I want, provided I can get it in a
smooth white finish. The panels will be in the top as well as the
sides, but I can support those with a lattice work to prevent them from
the cracking under their own weight.

One further question: I want to do some marquetry-like partial inlay in
the material. (The inlay will be metal, and proud of the surface.) I
have access to a pretty sophisticated CNC machining facility. Would
"cultured" products be workable with typical mill tooling? How about
with a handheld router?

Thanks to all for your suggestions.

/afb