Salt Dough Modeling Clay Recipe
(The following is a modification of the recipe found in Great Stuff: 100 Fun Projects for Kids,
that I tailored specifically for use with this Doctor Drill 'N Fill Play-Doh toy.)
Pour the flour, salt, water, and oil into a bowl and knead it with your hands until you get a clay-like consistency and the mixture no longer sticks to the sides. Mine came out fine on the first try, but if yours is too wet/sticky, add a bit more flour, or, if it's too dry, and a little more water.
Separate the clay into three portions* (3/5, 1/5, and 1/5). The three-fifths ball is for the teeth, and, as it's already an off-white color, there's nothing more to do, so set it aside for now. Take one of the one-fifth portions and add several drops of red food coloring to it (around 4-6, but you can use more, or less, to suit your own preferences). Knead the pigment into the clay until it's a uniform scarlet (take note that this process will also stain your hands, but it washes off easily enough). The red is for the mouth's tongue (and braces if you follow Hasbro's example, which I didn't, because nobody has red wires on their braces). With the white and red done, now it's time to mix the last color: gray. The original Play-Doh that came with the set was silver, but I was doubtful that I'd be able to replicate that hue with just red, blue, green, and yellow food coloring, so I opted for a bluish-gray instead. Take your last 1/5 portion of clay and add four drops of blue, two drops of red, and a drop of green food coloring to it (or some other combination if you feel that you can make a better shade than I came up with). Knead the clay until you get a uniform gray color. That hue is for the braces and tooth fillings. I didn't try it, but I imagine you could also mix some glitter into the gray clay to give it a metallic sheen. That's it, you're ready to play dentist!
This salt dough modeling clay should keep for several days if you keep it in an air-tight container (I used plastic wrap). Storing it inside a refrigerator also helps. If the clay starts to dry out while you're working with it (which it probably will, especially on a hot day), sprinkle the clay with a little water, knead that moisture in, and it should become pliable again.
* When I made my clay, I used a ratio of 1/2 white, 1/4 red, and 1/4 gray, but that was just barely enough white to fill the mouth with teeth, while I had lots of red and gray left over, hence, I adjusted the ratios so that you'll have more appropriate amounts of each color to work with than I did.