Bake cupcakes. Prepare cake batter following recipe instructions. Line muffin pan with color wheel cupcake liners, spoon batter into liners. Bake and cool.
Combine green icing color with blue to get dark green shown on fern leaf cookies. Tint icing. Using icing colors, tint white icing orange, yellow, bright pink and light pink; use combination above to create dark green. Tint enough of each color except dark green for both cookies and cupcakes.
Ice cupcakes. For the orange, lemon and watermelon; ice cupcakes smooth (for the watermelon cupcake, use the pink pouch icing). For the kiwi, pipe an approximately 1 in. circle in the center of cupcake using white pouch icing, then use the green pouch to ice the rest smooth.
Decorate cupcakes. Roll the edge of the watermelon cupcake in dark green colored sugar, the edge of the lemon in yellow nonpareils and the edge of the orange in orange nonpareils. Using tip number 3 from the decorating set and prepared decorating bag with white icing, pipe teardrop-shaped segments onto the lemon and orange cupcakes. Then use tip 3 with coupler and the black ready-to-use icing tube to pipe black bead seeds for the watermelon and black dot seeds for the kiwi.
Make cookies. Prepare cookies according to recipe instructions. Roll out cookies, then use round cutter and a knife to create at least two of each shape: circles cut in half, 2 in. squares, 2 in. x 3 in. and 4 in. x 1.5 in. rectangles, plus triangles with a 2 in. base and 2.5 in. sides. Bake and cool.
Decorate pineapple cookies. Using the 2 in. x 3 in. rectangle cookies, ice ¼ of cookie white, and ¾ yellow. Prepare decorating bag with tip 3 and yellow icing, then pipe lattice lines across yellow to resemble a pineapple. Use green pouch icing with included round tip to create leaves at the top.
Watermelon cookies. Using the triangle-shaped cookies, ice all but ⅛ in. at the base edge with pink pouch. Pipe a thin line of white pouch icing where pink icing ends, then pipe a thicker line of green icing using round tip for both. Take black ready-to-use icing and pipe three beads on each cookie for the seeds.
Grapefruit cookies. Ice 2 in. square cookies with light pink icing. Prepare decorating bag with brighter pink color and tip 3, then pipe teardrop-shaped outlines. Fill in teardrops, creating texture to resemble grapefruit segments.
Fern leaf cookies. Ice 4 in. x 1.5 in. rectangle cookies with white icing. Prepare a decorating bag with the dark green icing and tip 3, then pipe line down the center of each cookie, leaving a little room at the top. Outline and fill in long leaf shapes on each side of the line and at the tip.
Citrus cookies. Ice two half circles with yellow icing. Prepare decorating bag with orange icing and tip 3, repeating the same technique as the grapefruit cookies.
Kiwi cookies. Ice remaining half circles. With white pouch icing and round tip, pipe a semi-circle about 1 in. out from the center. Pipe the rest using the green pouch icing, smooth out. Add seeds right where green meets white using black ready-to-use icing tube and tip 3.