If this is the same All Metal with aluminum filler and liquid hardener it is very tough and difficult to feather.Auto body supply stores carry products made for very minor cosmetic repairs that dry fast and are easy to sand. One product is called "Icing" that is fairly liquid. Another product is heavier bodied from Duramix-Dont have the part # but their phone is 1-800-537-9204. you should sand base with at least 220 before applying.
