Run a knife around the edges of the Rice Krispie Treats and flip over onto a cutting board. Cut out 12 equally sized treats. Trim the edges so they have straight sides all the way around.
Start with the white and dark chocolate wafers. If you decorate in this order, you'll have an easier time keeping the chocolate warm.
Place chcolate melts in a microwave safe dish and heat in mocrowave on "MELT" setting. Stir vigorously every 30 seconds until the chocolate is smooth. The more you stir, the less heat you will have to use overall. Be careful and watch the temperature because if the chocolate gets too hot, the sugar will burn and you'll have to start over.
When the chocolate is melted and smooth, pour into icing bottles.
Get out 4 drinking glasses and fill halfway with very hot water. After the icing bottles are filled, place them in the hot water to keep them warm.
For the mummy, start with a small section ⅓ of the way from the top of your treat and pipe out a little dark chocolate. Stick on two candy eyes in the dark chocolate stripe. Use the white chocolate to pipe on stripes, making some horizontal and some diagonal to look like a wrapped mummy.
For Frankenstein, start with a lot of green chocolate for the base. When you have piped out a thick layer, tap the Rice Krispie Treat down on your work surface to smooth it out. Put on two candy eyes. Use the dark chocolate to give him hair and a mouth that looks like stitches.
For the Jack-O-Lantern, pipe out quite a bit of orange. Just like with the mummy, tap it on the counter to smooth it out. Using the dark chocolate, give it triangle shaped eyes, nose, and Jack-O-Lantern mouth.
They are ready to serve or you can bag them up for later. They travel well.