Gather supplies: white school glue, shaving cream, baking soda, contact lens solution (with boric acid), mixing bowl, spoon, measuring cups/spoons, optional food coloring, optional glitter
Measure glue: pour 1/2 cup (120 mL) white school glue into a mixing bowl
Add optional color: mix in a few drops of food coloring or glitter until evenly combined
Add shaving cream: add 1 to 2 cups shaving cream (about double the glue volume)
Mix: stir until the mixture looks thick and uniform
Add activator (small amounts): sprinkle in 1/4 teaspoon baking soda and mix thoroughly
Add contact lens solution: add 1 tablespoon contact lens solution and mix well
Repeat activator as needed: add contact lens solution 1 teaspoon at a time until slime pulls away from the bowl and feels less sticky
Rest: let slime sit 1 to 5 minutes
Knead: knead with clean hands until fluffy and smooth
Fix texture if needed: add more contact lens solution if too sticky; add a little more shaving cream if too stiff
Store: keep in an airtight container when not in use