The tempering process of melting and cooling will result in chocolate with a smooth texture, shiny finish, and pleasant snap.
Chop 3 pounds chocolate with a serrated knife. Place chopped chocolate in a dry metal bowl. Cut another pound of chocolate into larger chunks, and set aside.
In a saucepan, bring 1 to 2 inches water to a simmer. Set bowl of chocolate over saucepan, being careful not to let the water touch the bottom of bowl. Let chocolate melt, stirring gently with a rubber spatula, until it reaches 115 to 118 degrees on a chocolate thermometer (do not let thermometer touch bottom of bowl, and do not let any water get in melted chocolate). Turn off heat, and remove bowl from saucepan.
Add reserved chocolate pieces; stir until mixture cools to 78 or 79 degrees; remove any unmelted pieces. Place bowl back over pan of warm water (do not turn heat back on); stir until thermometer reaches 86 to 88 degrees. Immediately stir in food coloring until desired color is achieved; oil-based food coloring will give the best result.
Clamp molds tightly; pour chocolate into molds, and let set at room temperature until completely hardened, about 4 hours. Molds can be positioned upside down in saucepans, with rolled-up kitchen towels to hold them in place, while the chocolate sets.