There is some debate about the safety of borax..... I have used it and never had an issue. Just wash your hands and supervise any kid that might try to eat it!
2-4 oz bottles school glue(I used the cheap Rose Art stuff)
1/2 cup cold water
food coloring as desired
1 tsp borax powder
1/2 cup warm water
In a bowl mix the glue, cold water and food coloring.
In a measuring cup mix the borax and water until it is fully dissolved.
Pour the borax mix into the glue mix and stir well.
Keep stirring until it holds together well. Drain off any excess liquid.
I let it rest for 10-20 minutes and pour off any remaining liquid.....