Choose an object that you wish to cover with mosaic. Make sure it is clean and is free of dust.
Cut your mirror by lightly scoring it with a glass cutter. Place the scored mirror over a PVC tube so the score line is facing the same direction as tube and apply light pressure from above. Make sure that a towel is below the PVC pipe, creating a cushion and that you put a towel over the glass before pressing down so you aren't cut.
Shatter mirrored glass by covering it with a thick layer of newspaper and gently tapping with a hammer. Check after each stroke of the hammer to see if the mirror is broken to the size you desire.
Glue the mirrored mosaic pieces using either white glue, super glue or tile glue onto the object you are decorating. Let dry.
Mix powdered grout in a plastic cup with water until it is the consistency of toothpaste.
Scoop up the grout mixture and push it around the mirrors to fill any gaps. You will be able to remove excess grout off of the mirrors as it dries. Cover the entire object with grout, making sure it fills the entire depth of the gaps.
Remove large chunks of grout with your fingers as it begins to set, before it is completely dry. The color will begin to change and it will be thick, but not hard. Allow the piece to dry completely.
Use a damp sponge or paper towel to shine the mirror tiles on your dried mosaic object. Any dried residue from the grout should come off easily at this point.