Technically, yes maybe, but they have the plans availabe for free. If you bought the foam board, cut it yourself and built the plane installing your own electronics i would bet you would have far too much time and money into it to ever sell it for a profit at any kind of meaningful scale. If you built a few planes for your friends and they gave you a few bucks for time and effort there is no imaginable way it would be worth anyones time to take you to court...