DIY glass fibre plenum chamber? Bad idea?

[bruce plecan]

ref Tony Bryant:
Carbon fiber, or some other composite, yes to maybe,
Fiberglass nope.  Tried doing some fiberglas air cleaner
stuff years ago and the vibration killed it (4 cylinder)
Tried thin+thick none of it would last.  Maybe for
limited racing, but not steady street use.  Think I've
seen some Ford Aftermarket, Manifolds, Carbon Fiber
was a place with a web site something like Fiberglas
was going to make something and they had all kinds
of info, and people who seemingly who knew what was
what.  
HTH  Bruce