Mirror Disco Ball 40cm Mirror Disco Ball. 70s Disco ball is made of polystyrene foam with square mirror pieces covering it. Ball measures 40cm in diameter and has a ring attached for hanging. Create some disco fever at your next 70's party with this shiny disco ball - simply hang it from the ceiling and direct coloured lights at it to create a dazzling discotheque party setting! Ball is not motorised so will not consistently rotate. Please be aware due to the shape of the Mirror Balls a small amount of foam can be seen.