Two days in advance, make mortarboard and large tassel. Using Black Base Color, tint 12 oz. gum paste to desired shade of black (use 50 drops for black shown).
Using 20 in. fondant roller with yellow guide rings, roll out gum paste. Cut to 7 in. x 7 in. square. Let dry on cornstarch-dusted measuring mat, about 1 hour. Carefully transfer to cooling grid. Let dry for 48 hours. Reserve remaining black gum paste.
For large tassel, roll 1 in. ball white fondant into 5 in. long rope. Using 9 in. fondant roller with pink guide rings, roll out 1¼ in. ball white fondant. Cut into 2 in. x 2 in. square. Cut bottom 1 ½in. of square into seven strips, leaving ½ in. uncut. Using damp brush, attach top of square to end of 5 in. long rope. Wrap square around rope, forming tassel.
Using craft knife, carefully cut indent at top of strips, pinching gently to shape.
Carefully bend rope ½ in. from tassel, forming “L” shape. Lightly flatten other end of rope that will sit on mortarboard. Let dry on cornstarch-dusted measuring mat, about 1 hour. Carefully transfer to cooling grid. Let dry for 48 hours.