I’m not sure why my post warranted such a response. If you believe this isn’t possible, consider the skill and talent of our current truck aftermarket producers and the interest of our truck builders.
However, considering the material we’d need for the covering, resin might not be the best answer anyway, except for the framework, front cap, etc. I’m also aware that a functioning curtain isn’t possible either, and Italeri makes a European curtain side too, but it’s not much help to the North American builders.
Auslowe has made curtainside trailers, so there is already an aftermarket presence, though an Australian design.
Regardless, a few guys have scratchbuilt a curtainside. The upcoming Moebius kit is a great starting point for such a project, making a bunch of the work easier. I’m willing to scratchbuild, but I always have faith in the aftermarket.