Make candy clay, 1 day in advance. Prepare candy clay following recipe directions. Let set overnight.
Make two-tone candy clay strips.
Divide candy clay into four portions; knead until softened. Use candy colors to tint one portion pink, one green, one blue and one violet. Knead each portion of candy clay, then divide in half. Tint one half of each color slightly darker. Use 9 in. fondant roller with purple guide rings to roll out each light and dark shade of candy clay to 1/8 in. thick and 20 in. long.
Use fondant trimmer to cut each color into strips 3/4 in. x 20 in.
Place the lighter strip on top of darker strip.
Use fondant roller to lightly roll the two strips together. Trim strips to 1/2 in. x 20 in.
Make cupcakes. Prepare cupcake batter following recipe directions. Bake and cool cupcakes. Prepare buttercream icing following recipe directions. Use angled spatula to ice top of cupcakes smooth.
Make candy clay ribbon flower. Position strips on cupcakes, forming a coil shape, starting at center.