i am a powdercoater myself and have done alot of wrinkle red stuff. 4 coats seem like alot for paint. when i do powder i only use about 2-3 mils and it wrinkles up as you would expect. curing it in the oven is a good idea but 200 seems too low and 300 is too hot for paint. if you do it again try it in the middle..around 240-250 for about 15-20 minutes. or you could send them to me and ill do them for $75 plus shipping.