I've been wish-book reading FarmTek's website for a bunch of years.
Looking at the PDF on their PolyMax: it will expand and contract up to 1% with temperature variations
meaning slotted mounting using a over-riding molding.
I could see either 'wavy' surfaces from heave and shrink with random fasteners binding and throwing all the others off to the side of their 'oversized' bores to where they bind again to skew the whole board and build more ripple - or bending stamped sheet metal supports... or over-tighted clamping screws with counter-sunk washers blowing out the corners from stress cracks.
Cutting Boards and polyethylene at The Cutting Board Factory
<--- another source of polymer board stocks. I'm thinking of using some of their cut-off specials as a wiring chase similar to a computer room's wire chase down one side above the floor, and counter tops work-edge board.
Their polyethylene based polymer "Plastic - Artificial - Synthetic ICE sheet" might make a heck of a custom radius shower stall.