Thanks for the info. I searched around here for Sintra and couldn’t find a place that would sell it to me, so the PVC looked like an alternative. Cheap enough that if I screw or up it won’t be too bad.
The pieces are fairly small, like 20” x 50”. Weight might be an installation factor...
I haven’t done it yet, but I’m planning to use 1/4” PVC trim board. Available in 4x8s.
https://www.homedepot.com/p/1-4-in-x-48-in-x-8-ft-White-PVC-Trim-H060AWS3/309355877#overlay