Hmmm...just got a vented front mudguard from Casoli.
Well not exactly from them directly, I got it for £70 off eBay but it's a brand new Casoli item that had only been on the bike for 200 miles. I believe the seller - it's spotless.
Anyhow, I can't see any glass fibre involved in it's construction and the quality looks top notch to me