One of my favorites involves homemade-kind of edible (not going to kill you, not too tasty though), fingerpaint! This recipe takes no time at all and is so simple the kids can help with most of it! I will often make this recipe before lunch or dinner, put it in the freezer to cool while we eat, then pull it out after for lots of messy (but easy to clean!) fun!!
Homemade Finger Paints
3 Tbsp Sugar
1/2 tsp Salt
1/2 c. Corn Starch
2 c. Water
Combine ingredients in a small sauce pan and whisk until smooth, warm them up on the stove, stirring occasionally until mixture thickens. When it thickens, it will all at once. Seriously, it will be thin, then BOOM thick! Divide into containers and add food coloring as desired. Make sure you let it cool!
Now for my secret ingredient to non-messy fun....
No kidding! Our bathtub is white, so it is extra awesome, but I just strip everyone down to their diapers and stick them in the tub with paint. Then the boys can put paint all over the tub and themselves, and keep the mess maintained. When they're getting bored I fill up the tub with water and let them get the paint off of the tub and themselves. Then I just drain the water, refill it, and clean the kiddos for real!
(Did you notice the dirty hand in the corner there?)
I'm not kidding, you can get 2 hours of fun out of it!
Bonus points: the bathtub gets clean!