Introduction: Rice Krispie Treat Watermelon. 
We were invited to a couple of 4th of July parties this year and needed a treat to bring. So I came up with the Rice Krispie Treat Watermelon. My kids love faux-foods, and this one we came up with on our own.
Strawberry flavored marshmallow Rice Krispie treats with dried blueberry "seeds" covered with fondant. Step 1: Ingredients. I used the standard Rice Krispie Ceral Treat recipe. I had to double it to make mini watermelon. So buy 1 large box of cereal and 2 bags of strawberry marshmallows.
You still need to make in two separate batches to make it easier to handle.
Watermelon Filling
3 Tablespoons of butter
6 Cups of Rice Krispie Treat Cereal
1 10 oz. bag of Kraft Jet-Puffed Strawberry Marshmallows
1/4 Cup of dried blueberries
Watermelon Skin
8 oz of mini marshmallows (half a bag)
1 pound of powdered sugar
water
shortening (for your hands) Step 2: Watermelon Skin. 
The skin of the watermelon is made from fondant. Do not use pre-made fondant from a bucket. Make you own. The recipe I used is from Peggy Weaver's site.http://whatscookingamerica.net/PegW/Fondant.htm
Just follow the directions on her site. It is the best tasting fondant and is easy to make. Once you have the base fondant made start adding color. I started with equal parts green and yellow. Add just a few drops at a time and work it in. Once you have a good yellowish-green put a third of it in a plastic bag. Now start darkening the remain 2/3 with more green and some blue. Again work in the colors a few drops at a time before adding more. If your green is too bright add a drop of red. Compare to you light green to judge your colors. Put the darker green in a baggie and place them in the refrigerator. Step 3: Watermelon Insides. Clean up from the previous step. I made my treats using the microwave. I first melted three tablespoons of butter. Then add one bag of StrawberryMallows and coat with butter. I heated them in 30 second increments. Stir in between each heating. After a minute most of them should be melted, if not continue to mix. There should be enough heat to melt the rest.
I added about 5 drops of red food coloring, I wanted the inside to be a little more pink. Now add 6 cups of Rice Krispie Cereal. Stir them in with the dried blueberries. (Our first thought was to use chocolate chips, but they would have melted too easily.)
Spread the mixture on to a greased cookie sheet to let it cool. Now repeat the recipe again and add the second batch on top of the first.
When it has cooled enough to handle, roll it up into a log and cover with waxed paper. It needs to cool for an hour or longer. If it is too warm it will loose it's shape. Step 4: Forming the Melon. Use your hands and starting shaping in to melon. My wife thought it looked like raw hamburger and my daughter thought it looked like a brain. If it holds it shape then your are ready for the fondant. If it starts to sag, let it dry out some more.
Get the fondant it out and knead it some. It will warm up quickly. Use powdered sugar to keep it from sticking to the counter and rolling pin.
I used a piece of plastic wrap to get the size I need to roll out. Make sure your stripes are in the right direction. Step 5: Finshing Touches. Wrap the Rice Krispie shape up in the fondant and work out and seams. You can add more stripes over the green and just smooth them in. If it is getting sticky add a little powdered sugar and rub it in.
If you have it outside slice it quick, the humidity make the "skin" stick together. It may not be as refreshing as a good watermelon, but you can make them year round.