Cameras will be a problem. Maybe making a friend at the hotel or posing as a security consultant will get you blank cards. Which ever way you proceed, it looks like a major project. Could be fun though... Hotel security is big business! You would a VERY knowledgeable thief to do this.

viciousmu (or however you spell it), most hotels nowadays can't make a "Master Key" for all rooms. The room service agents only get keys to their designated rooms to clean. This is to prevent theft.