TRIM rounded tops off pound cakes. Stack 2 of the cakes together using whipped topping in between the layers to hold together. (This is the back of the fire truck.)
CUT 1/3 off the end of the remaining cake. Lay the 2/3 portion of cake in front of and level with the bottom of stacked pound cakes. Place the 1/3 portion vertically on top to form an L-shape against the 2 stacked cakes. (This will form the cab of the truck and be slightly higher than the 2 stacked pound cakes. See photograph.)
TINT whipped topping with red or yellow food coloring until desired color is achieved. Frost entire fire truck. Attach 3 donuts on each side of the truck for wheels. Add pretzel sticks to create ladders on the sides and back of truck.
LAY licorice on top of the truck to make a water hose. Outline windows and doors with licorice. Place assorted candies on top of the cab as lights and on front of the truck for headlights. Refrigerate until ready to serve.