I had never heard of the stuff before your post. My guess is you'll be stuck with salvaged material. Good luck.

We have a house covered inside and out with Weldtex and have the same issue -- love the stuff and want to maintain it, but no obvious sources. So we're working with a guy in Northern California (Jeff Nichols) who does specialty plywood for Eichler homes. Here's his info: http://www.groovedplywoodsiding.com/

We shipped him a deposit (to cover his expenses with experimentation) a virgin piece of Weldtex (no paint or sealer) and a laser cut profile of the groove pattern and he's working on finding someone to make the blades he needs to cut the pattern into some test plywood.

So far he's gotten some close approximations but we haven't cracked the nut yet. However, he's motivated and so are we, because if we can't figure out, then our home is very vulnerable (the siding on the outside is now 60 years old) to losing some of the original look--which would KILL us because we love it.

Please feel free to contact Jeff. If he has 2 customers for the stuff that makes it easier for everyone!

And if the piece you need to replace is a small one, let's talk -- because we actually used a set of laser cut pieces of steel to create a 36' wide giant comb which we then dragged through some heavy painters putty to create 4 panels for our garage doors that look very convincingly Weldtex-like. Depending on what you need to do, we could talk about loaning you this crazy re-pro comb thing to make your own fake Weldtex.

Yes, Weldtex is an incredible material. I have a house practically made of the stuff and have had to meld scraps to replace missing pieces. I hope someone
can recreate it!