Who says real men don't wear foundation? Mr. ''T3'' himself, Arnold Schwarzenegger, was prettiness personified after being made up by M.A.C cosmetics artist David Biard during the Cannes film festival last month. The secret behind Ah-nuld's glowing yet carefully contoured look? M.A.C Blot Powder and Studio Tech Foundation. ''He wanted to look really natural and really fresh,'' dishes Biard. ''His bone structure is really good and there are no imperfections, so I just did something very light to make him gorgeous.'' And did the star -- who Biard says was ''very, very comfortable wearing makeup'' -- have any special requests? ''He didn't want to look so tan.'' Ben Affleck, take note.