Soften modeling chocolate (knead until smooth). Make a ball (approximately 1-inch in diameter) for the base of the rose. Make four 1/4-inch balls for the first set of petals. Make three 1/2-inch balls for the second set of petals. Make five 3/4-inch balls for the third set of petals.
Pinch the 1/4-inch balls until flat, then pinch the edges to add texture.
Take first petal, attach to 1-inch ball, and form a cone (this may require a little water).
Take a flattened petal, curve it as shown, and roll the opposite edges with a toothpick.
Flip petal over and press thumb into the center to shape it.
Start adding petals one at a time, keeping the height a tiny bit higher than the center cone.
Overlap each petal with the petal next to it.
Use smoothing tool to attach.
Using your fingers, curl back the tips of the petal to give it more dimension.
Repeat the process using the three 1/2-inch balls for the second set of petals and using the five 3/4-inch balls for the third set of petals. Continue until you have a rose the size you desire!