As said in the other post, the covers are cheap. If you decide to go with the fiberglass, clean your vent real well. You might want to rough the surface up with a piece of sand paper slightly.
You can cut the cloth to the size you are going to use.
Wear disposable latex gloves.
Mix the hardener and resin and stir well. You can use a wood paint mixer for this. A small amount goes a long way.
Make sure you put something under and around the area you are going to work. Coat the area with the resin./hardener mix. {a cheap throwaway brush would be good for this}. After the area has been coated apply the cloth. After the cloth is in place you can put another coat of resin/hardener on to soak the cloth real well. The cloth will sometimes stretch so it might now be too large for your work area. You can use a sharp knife to trim it down after it dries if needed.
After this sets up you can put another coat of resin/hardener on if needed.
Drying time depends on the temp outside and the amount of hardener used along with how well you stir the hardener and resin.
You will need several brushes, gloves and containers to mix in. The stick you use to stir can be used again as long as it didn't get dirty.
Done right this should last a long time.
It should work fine. Good luck!
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