Elmer’s Washable Clear Glue, 1 Gallon | $10 | Amazon
Slime is objectively fun, so whip up a bunch of batches with this gallon of Elmer’s Washable Clear Glue for just $10 (you will also need baking soda and contact solution, or Elmer’s Magic Liquid, plus any food coloring and/or glitter of your choosing). I guess, if you insist, the glue could also be used for, uh, gluing things, but really, slime is the goal here, OK?