There are so many different ways to make this stuff. Check out your supplies in the cupboard before buying anything new. Makes a relatively firm ball of silly putty like substance.
An assortment of resources that may include -
liquid glue (PVA / School Glue)
Borax or liquid starch or laundry liquid
bowls / cup (for mixing and for taking home in?)
Stick (for mixing)
Copy and paste the link above into your web address bar to find a selection of different silly putty recipies to try.