No. They are hand-laminated fiberglass. I have a local SoCal friend who's Sy I've worked on for years that purchased two rockers and two front arches from the current source. IIRC, $1,800. I refused to work with the parts. The rockers had about 2" of front to rear bend in them, had been hand-trimmed with a sabre saw, and were such a thick lay-up that they were totally inflexible and too thick for the door to close if they were mounted on the stock rocker hardware. I didn't see how ANY amount of work would make them usable. The front arches to fender gap was so irregular (hand-trimmed) and the tabs so stiff, they didn't really fit at all. Looked like WAY too much work and aggravation; I refused to do it. This is all long before you get to painting the surface.
I worked with another local guy that purchased a LR Ty corner. Again, it was a very thick lay-up, had been hand trimmed, and the tabs were rigid and in the incorrect position. It took about 3 hours to get the fit close enough. After the part was painted, it took me another three hours to jigger-rig the mounting and get it to look right. The bolt into the rear arch was a bitch.
There were several pieces of fiberglass cladding on DesertSy when I purchased it, but they came from the former source. They were thinner, more compliant, and the fit was fine. The current people need to work on their lay-up schedule and endeavor to keep the parts thin enough to be compliant and the final gaps to be usable (the top rail of the rocker can't be so thick that the door can't close!). They also need to work on the way they trim the flash off after the part comes out of the mold. On the Sy rockers I looked at last year, they made more work for the installer by the rough-cut they left than if they had not trimmed them at all.
These parts could be valuable to the peeps still trying to restore or preserve SyTy's. But the present fit and lay-up presents LOTS of work and challenges for the installer to get them on the truck with decent fit and finish. Until quality improves, I'll pass. Too much work to make them fit at all, much less to the tolerances I desire on my projects.