I wanna try my hand at making a small plug out of green foam as the base material. Wondering what is used to fill the void, gaps, and dings before sealing? Also should I glass the plug? If so, should I fill then glass or glass than fill? My guess would be fill than glass. After glassing I was thinking of using a high build primer sand smooth before paint. I'm afraid to ask because I'm sure that there are purist, but is there a rattle can option for high build primer and and paint?