If you want to fiberglass over plywood, the process is actually quite simple. First, make sure that the plywood surface is clean and free of any debris or contaminants. Next, apply a layer of resin to the plywood surface using a brush or roller. Once the resin has been applied, lay down a layer of fiberglass cloth over top of it. Then, wet out the cloth with more resin and let it cure for 24 hours. After the initial curing period, you can then sand down the surface to create a smooth finish.