Just reread the thread. .JB weld won’t penetrate fiberglass cloth.
What TrailBlazinMan said is right. The gel will not penetrate cloth either. Also, there’s the liquid (which will penetrate cloth).
When I said Acraglas, I was talking about the gel. To get fiber into the gel, it has to be chipped up fairly fine and mixed with the gel before you use the hardener. Dunno about fiberglass, but kevlar and carbon mix in well. I don’t see why fiberglass wouldn’t work because epoxy resins tend to work with anything, but there’s no real advantage to doing it … kevlar and carbon will NOT work with polyester resins (the usual stuff sold as fiberglass resin)
Other guys will have better advise. I have a tendency towards overkill. If you’re just needing a spacer, most of this stuff about fiber and such is not needed. JB weld by itself might even work? I wouldn't do it ... but ... Don't try to use it with cloth, though.
Keep smiling ... it'll just make 'em wonder what you're up to...