In advance, tint rolled fondant: 30 oz. yellow, 24 oz. leaf green, and flower colors you’d like to make. Spread Roll & Cut Mat with a thin layer of shortening. Roll out fondant 1/8 to 1/16 in. thick. Cut with Calla Lily Cutter.
On thin foam, use ball tool, keeping it mostly on the foam, to thin flower edges by sliding tool around petal edge.
Dust Calla Lily former with cornstarch or confectioners’ sugar. Position former over cut out fondant, with wide end of former toward point of heart-shaped petal and pointed end of former at the indented end of the petal. Wrap 1 side of petal around former. Brush edge of rounded petal portion with glue adhesive. Wrap other side of petal so it overlaps first petal; attach to make a cone-shaped flower. Gently furl back edge of overlapping petal. Stand former upright and set aside to dry.
Roll out green fondant 1/8 in. thick; cut out leaves in varying sizes. Place on thin foam; mark vein lines using small end of veining tool, starting with center line; place in flower formers to dry.
Roll out green fondant 1/16 in. thick. Use medium Round Cut-Out to cut circle; cut circle in half. Brush small amount of fondant adhesive on one half circle. Position the center of straight edge overhanging the point of the cone on the side opposite the flower seam, with the rounded edge on the flower. Wrap around the Calla Lily and press gently to attach, trying to line up the overlap. Set aside to dry. If desired, brush Pearl Dust on flower petals.
Roll out yellow fondant 1/8 in. thick; cut circle with medium Round Cut-Out. Cut circle in half. Use 1 half to make flower center; roll into a ball, then elongate to a cone about 1-1/4 in. long. Brush with fondant adhesive; roll in Yellow Pearl Dust or Colored Sugar. Set aside to partially dry. Brush fondant adhesive on bottom of calla lily center; insert into flower and gently press to attach. Let dry.
Bake favorite cake recipe in two 7.75 x 5.5 in. oval baking pans; cool completely. Stack cooled cake layers on a foil-wrapped cake board cut to size using buttercream icing as a filling. Prepare cake for fondant with buttercream icing.
Roll out yellow fondant 1/4 in. thick; cover cake. Smooth with Easy-Glide Smoother or hands. Make fondant rope about 1/4 in. diameter; position around bottom edge of cake. Imprint rope by pressing shell end of Gum Paste Tool.
Roll out green fondant 1/8 in. thick; cut out pieces following pattern. Cut out decoration with Decorative Punch Set. Attach to top edge of cake. Arrange Calla Lilies and leaves on cake top.