How about homemade clay? My kids love to make it and decorate their creations.
I found this recipe on
Family Fun, Games, Activities & Craft Ideas for Kids & Holiday Printables - FamilyEducation.com
Modeling Clay
Materials
* 2 cups salt
* 2/3 cups water
* Saucepan
* 1 cup cornstarch
* 1/2 cup cold water
Directions
1. Stir salt and water in a saucepan over heat 4-5 minutes.
2. Remove from heat; add cornstarch and cold water.
3. Stir until smooth; return to heat and cook until thick.
4. Allow the clay to cool, then shape as desired.
5. When dry, decorate with paint, markers, glitter, and so on.
6. If you like, finish with clear acrylic spray or clear nail polish.
7. Store unused clay in a Ziploc bag.
I have never tried this recipe. We use a similar one, but of course I can not find it right now. Check out that website though--there is tons of ideas for kids and crafts.