1. Melt candy melts as package label directs. Dip bottoms of gingerbread cookies as desired. Shake off excess and place cookies on a parchment-lined baking sheet. Refrigerate to harden.
2. Divide royal icing into 3 small bowls. Leave 1 batch white, tint 1 red and tint third green. Spoon each batch into pastry bags fitted with small plain tips. (If you have only 1 tip, decorate using 1 color at a time.) Pipe icing to make faces and other decorations, and to attach M&M's Minis.
3. Attach Minis as desired for buttons and belts.