This creative cake decoration for Martha's showstopping Easter cake is made out of gum paste, which is an edible, pliable candy product that is easy to mold into the shape of your choice, and then hardens when it is left to dry overnight.
Dip a toothpick into gel paste and swipe through gum paste, starting with 2 swipes of brown and 1 swipe of black. (Use a fresh toothpick to add more color.) Knead until color is even, adding more gel paste as desired.
Lightly dust a work surface with confectioners' sugar. Roll gum paste into a rectangle, 1/8 inch thick. Cover with a wood-grain impression mat and firmly press with a rolling pin to create pattern.
Using a pizza cutter or chef's knife, cut gum paste rectangle into vertical strips, each 1/3 inch wide. Separate strips and cut crosswise into slats and posts: 12 posts, each 2 3/4 inches long; 12 short slats (for garden entrances), each 3 1/2 inches long, leaving one end squared and cutting the other on the bias; and 18 longer slats (for sides of cake), each 5 inches long, both ends trimmed on the bias.
Transfer cut pieces to parchment-lined baking sheets and let stand until firm and dry, about 8 hours or overnight. Dried fence pieces can be stored on baking sheets, covered with parchment, at room temperature up to 3 days.
To create the look of a realistic wooden fence, you'll need a textured mat that imprints a faux-bois finish into the gray-tinted gum paste.