John and Elna Foust used to have a store called the Fish Haus
where they sold Foust's Fly Foam and a Foust PolyChute Tool
as well as all the usual fly tying goodies.

That store no longer exists. But Foust's Fly foam is and was (I think)
just
Evazote foam, which you can buy at many other locations.
Search for Evazote at Google.