Unlike Peeta, I am a decidedly amateur cake decorator, so I knew I wasn't up to assembling a Mockingjay. I settled for one of Katniss's arrows. I had also, with the help of a friend whose sister works at Borders, snagged a real Mockingjay pin as a surprise gift, so I decided to clip it to some wax paper and adapt as a cake topper; that's it on the arrowhead, though it's hard to see in the picture.
To make the arrow: bake a 9 by 13 inch cake. Freeze, then cut lengthways into 3 horizontal strips. The two from the edges will be placed end to end for the arrow shaft. From the middle strip, cut one right triangle from one side, and another from the opposite end, leaving a parallelogram-shaped wedge in the center. Slice this longways down the middle, so you get two smaller, thinner parallelograms. Turn one triangle and one parallelogram upside down. You can now place the two triangles back to back to make the arrowhead, and the parallelograms on the other for the tail feathers. Frost with your favorite icing, pipe birthday greetings or a favorite line onto the shaft and score the frosting on the feather with fork tines. Add Mockingjay pin, if available.
Note: this is a long cake, almost three feet. I used a foam board covered in plastic wrap for a tray.
May the odds be ever in your favor.