Stick the fourth gumdrop onto the ends. Comments Cannonballs are often stacked in a tetrahedral array. You can create such a stack by glueing marbles together. You can create a tetrahedral lattice out of 20 gumdrops and 40 toothpicks. The octahedron has eight triangular faces, six vertices, and 12 edges.
Construction Begin by sticking four toothpicks and four gumdrops together to form a square.
Take four more toothpicks and one more gumdrop. Build a pyramid on the square by sticking a toothpick into each gumdrop and joining the ends with the new gumdrop. Turn the pyramid upsidedown. Take four more toothpicks and another gumdrop. Build another pyramid on the other side of the square.