If you are making parts out of epoxy resin and fiberglass cloth, then you need to use FINISHEpoxy not 30 min or even 60 min. They bothe had thiskners added to them and make them harder to go through the glass cloth. West Systems is about the same thing, thin epoxy with no thickner added. You wet out the cloth and then let it set up over night. The next day, if you need to add another layer, do it then. Don't wait until it is compleately set up or it won't stick right. If you are using a mold, make sure yo uhave plenty of mold release on it or you will glue them together forever. Spread out each application of epoxy with some kind of spreader. Plastic, rubber, or balsa all work to spread the epoxy out and cover the part good. Wype up the excess and let it sit over night again. If you don't want to put any more layers of glass on, then fill the weve with a final coat of finish epoxy and use a spreader again and just fill the weave, don't lump it up all over the place or you will have much more weight then you need. Do your sanding the first day after it sets up if possible. Anything longer then 1 day and it starts sanding like cement.

Ed