Select a ball. There is no right or wrong size with a disco ball, so you can use any size you wish. Choose a material that is strong enough to hold the mirror chips and strong enough to by hung without deflating. Solid rubber, polystyrene or plastic materials work well.
Add a piece of string to your ball so that you can hang it. Make two incisions in the ball, about an inch apart, then thread the piece of string through and knot.
Paint your ball silver to make the small gaps less obvious.
Glue mirror chips to the ball in single rows. Mirror chips can be purchased at craft stores. Use small, square chips and for a more even finish, start at the top of the ball and work your way down. Glue the mirrors in straight rows for a more professional finish.
Use your first row as a guide and cover the entire ball in mirror chips. Continue gluing the mirror chips until the whole ball is covered. It is a good idea to turn the ball over when you are ready to glue mirror chips to the bottom half. By doing this, you will be working on a section that already has a dried row of mirrors.