Knead together gum paste and shortening on a clean work surface until shortening is fully incorporated and gum paste is soft and malleable. (It may be easier to work with half of the gum paste and shortening at a time.) Wrap half of the gum paste mixture tightly in plastic wrap, and set aside. Wearing gloves, knead 10 drops of red food coloring into remaining half of gum paste mixture until thoroughly blended, kneading in 1 more drop at a time until desired color is reached.

To make petals: Use a rolling pin to roll the red gum paste mixture to 1/8-inch thickness. Cut 12 circles out of the gum paste mixture using a 1-inch round cutter. Cut 24 circles using a 2-inch round cutter, rerolling scraps as needed. (To prevent gum paste mixture from drying or cracking, work quickly and keep it covered with plastic wrap or a damp paper towel as you go.)

Using small scissors, cut each circle into a teardrop shape with a pointed end.

Place each petal on foam mat, and using the rounded bottom of a measuring teaspoon, gently and gradually smooth edges of petal until edges are slightly thinner. Place 3 or 4 petals in bottom and against side of a small bowl, shaping each petal to curvature of bowl. (Do not overlap petals.) Let stand, uncovered, overnight.

To make stamens: Unwrap remaining half of gum paste mixture; pinch off 4 pea-size balls, and re-wrap remaining gum paste mixture. Roll each ball into a 1-inch-long cylinder. Using small scissors, cut cylinders in half lengthwise, stopping about halfway. Cut each half in half again to create quarters. Cut each quarter into thirds. Stand cylinders upright on a work surface; let stand, uncovered, overnight.

To make leaves: Wearing gloves, knead 10 drops of green food coloring into reserved portion of gum paste mixture from Step 3 until thoroughly blended, kneading in 1 more drop at a time until color resembles the deep green shade of a camellia leaf. 

Roll mixture into a 1/8-inch-thick sheet. Cut out about 24 leaves using a leaf-shaped cutter. (Or, using a 2-inch round cutter, cut into about 24 circles, and, using small scissors, trim into a leaf shape.)

Place each leaf on foam mat, and, using rounded bottom of a measuring teaspoon, gently and gradually smooth edges of leaf until edges are slightly thinner. Using dull side of a paring knife, create a vein pattern on the leaves. (If using a leaf-shaped mold, press each leaf into mold; and gently remove.) Place leaves on a sheet of parchment paper, and let stand, uncovered, overnight.

To make flowers: Place a 1-inch-square piece of paper towel in center of a small bowl. Arrange 3 large petals in bowl, allowing the narrow ends to overlap in the bottom center of the bowl. Dab a generous amount of edible glue in between each petal end, and gently press to adhere.  Place 3 large petals on top, arranging them in gaps of petals already in bowl. Dab a generous amount of edible glue in and around the center of the petals, and press to adhere. Place a small ball of aluminum foil behind each petal to keep layers of petals from touching. Arrange 3 small petals on top of gaps of petals in bowl. Dab a generous amount of edible glue in and around the center of the petals. Press to adhere. Place a small ball of aluminum foil behind each petal to keep layers of petals from touching. Repeat with remaining large and small petals in 3 separate bowls to form 3 more flowers.

Using a food-safe paintbrush, brush 1 stamen with a mixture of green and yellow luster dust; blow off excess.

Dab a small amount of edible glue on flat end of stamen, and press into center of 1 flower. Place small aluminum foil balls around the stamen to hold upright. Repeat with remaining stamens and flowers. Let stand, uncovered, at least 24 hours or up to 48 hours.

Once the glue has dried, remove and discard the aluminum foil balls from between petals and from around stamens; remove and discard paper towel squares. Place camellia flowers on top of frosted cake, pressing lightly to secure. Arrange leaves around each flower or along bottom of cake, forming a garland. (The flowers will keep in an airtight container in a cool, dry place up to 4 months.)