For each rat, trim half a cake doughnut to narrow one end into a pointy nose shape. Freeze it for a few hours, then cover it with chocolate frosting, working on cut surfaces first (skip the bottom), then the uncut areas. Drag a plastic fork through the frosting for a furry look. Using a pair of tweezers, add a sugar pearl for a nose, then insert sprinkles as whiskers. Attach chocolate-covered sunflower seeds for eyes and sliced almonds for ears. With a skewer, poke a hole for the tail, then insert an 8-inch length of licorice lace.