I did a quick google search for terraflex. Please understand that I am in no way any kind of authority here, but from reading the description - Elasticized Polystyrene - I don't
think that it, by itself, would be approvable. I'd imagine that you'd definitely have to resin or bondo or rondo or whatever.
I'd recommend visiting
this thread and picking one of the App Team members and just sending them a PM.
I'm sorry I don't have a better answer for you.
