Divide your glue into as many bowls as you want colors of slime. For this recipe, we used 3 cups of glue and 3 colors, but you can use less glue if you prefer (I just wanted to be sure to get some great pictures).
Add neon food dye or acrylic paint (about 1/2 teaspoon per 1 cup of glue). Stir the water into the glue, about 2 Tablespoons to start.
Next, add the shaving cream. About 1 1/2 cups to start, until you achieve a nice fluffy texture. It will continue to get thick and puffy as you stir. (We can add up to 3 cups of shaving cream per 1 cup of glue, depending on how fluffy we want it.)
Finally, add the contact solution – 5 Tablespoons per cup of glue. Keep stirring everything with your spatula and adjust as needed. Once the slime is cohesive, no longer sticky or appearing to have any liquid in the mixture, start kneading the slime – this is going to help it be less sticky (just like making homemade play dough).
Knead the slime for at least 3 minutes before adding any more ingredients to adjust. If adding the color foil, once the slime has been thoroughly kneaded, lay it out in strips or blobs on a clean surface.
Gently place your color foil over the slime and then gently press down on the foil to see it break apart and start making a pretty, cracked pattern on the slime.