This is an environmentally friendly sidewalk paint. It washes off very easily and will not harm plumbing or plants...cornstarch is all natural and biodegradable. It is also very inexpensive!
1/4 cup cornstarch
1/4 cup water
6 to 8 drops of food coloring
Put cornstarch in a small plastic bowl and gradually stir in the cold water. Add your desired food coloring and stir. If the paint still feels to dry, just add a little more water until you get the consistency you prefer. (I didn't need to add any more water to mine)
Repeat the process to create different colors.