M_Boats: Epoxy

Is there an epoxy that is REALLY easy to mix to different consistencies (runny for soaking balsa, tacky for filling holes, etc.), that can be purchased in small quantities and that is carried by any local hardare store? My two most important criteria are versatility and ease of use. I want an epoxy that will cure correctly in hot humid weather. Am I asking too much? I'm not really concerned about price, within reason. Thanks!