Roll out gum paste 1/16 in. thick. Using 3rd largest heart from Nesting Heart Set, cut one heart for each lily. Trim off rounded bottom to make a straight edge. Place on thin foam lightly dusted with cornstarch and ruffle sides using pointed modeling stick from Floral Collection Flower Making Set.
Position modeling stick over center, 3/4 in. from bottom edge. Roll one side of petal over to center. Brush 1/4 in. of top edge with adhesive. Wrap other edge over and around to form cone; pinch and smooth seams to seal. Gently shape top edge. Allow to dry on paper cone dusted with cornstarch.
Use tip 3 to pipe a bit of royal icing into center. Cut 3 stamens in half and insert 6 tips into center of each lily; let dry.