Make and attach disco ball tiles also 1 day in advance. Prepare thinned fondant adhesive following recipe directions. Use 9 in. fondant roller with pink guide rings to roll out reserved gray fondant 1/16 in. thick. Brush top with thinned fondant adhesive. Let dry, about 5 to 10 minutes. Brush top with silver Pearl Dust edible accents. Use knife to cut 200 squares, each 3/8 in. x 3/8 in., and a circle, 3/8 in. dia. for top of ball.
Use tip of craft knife to make a hole in flat side of ball to fit dowel rod. Prop ball on a towel to prevent rolling. Brush center seam with thinned fondant adhesive. Attach tiles around seam. Repeat to attach rows of tiles from center to top of ball, keeping top edge of rows even and staggering seams. Cut and attach small triangles of silver fondant to fill in gaps. For last row at top, trim sides at a slight angle to fit. Attach 3/8 in. circle to top. Repeat attaching tiles to bottom half of ball, without a circle at bottom. Brush ball with silver Pearl Dust edible accents.