1. Using the star tip and icing, pipe a thick line of icing along the front edges of the roof. Press candy canes into the icing. Pipe a large star at peak of roof where candy canes join. Let dry for 15 minutes.
2. Using a small spatula and icing, spread a layer of icing on one side of the roof. Place overlapping rows of peppermint candies on the roof, starting with bottom row and pressing into icing. Immediately sprinkle roof with sugar to add a "sparkle" if desired. Decorate other side of roof. Brush off excess sugar in areas where you wish to add the "Santa's Workshop" sign and icicles. Wait 15 minutes to let icing set.
3. To make the "Santa's Workshop" sign, cut a piece of a graham cracker the same size as the paper sign. Spread one side of the cracker with a thin layer of white icing. Place paper design on icing and gently smooth surface. Attach to roof with several dots of icing. Hold in place until set. Allow to dry.
4. To decorate the ridge of the roof, brush off excess sugar. Use the star tip to pipe a line of icing along the ridge. Place a row of red licorice candies in icing on ridge. Allow to dry.
5. To make icicles, use the round tip and icing Place pieces of waxed paper against walls of workshop to protect designs while making icicles.