Health Tip: The Tea Tree oil is a fantastic germ killer. Play dough is a warm, moist environment. This makes it a perfect breeding ground for bacteria. Some people can be sensitive to Tea Tree oil, so do a skin patch test on everyone who will be using it. If you do not use some kind of germ fighting essential oil, you need to make the play dough more frequently for sanitation reasons.
There's no need to skip out on Play-Doh brand toys due to the cost of the replacement dough. You can replace the dough with easy homemade recipes. This is a double batch of the above recipe without food coloring.