Mixers and mixing enclosures for drums, tanks, and pails prepare contents inside containers for dispensing. Drum, tank, and pail propeller mixers insert into containers or open bungs to agitate contents with moving blades. Drum and pail roller and tumbler mixers blend contents insides closed containers without having to open or contact them. Safety enclosures for roller and tumbler mixers create barriers between workers and drum rollers and tumblers.