Have you heard of milk plastic before? Not only is it a project you can do with kids, but it’s also how they made many plastics before the advent of synthetic plastics! Many of those old buttons in a jar you have from your grandma are probably milk plastic (actually called casein plastic, Galalith, or Erinoid). They have a beautiful marbled or tortoise shell look, and are often pastel colored or two toned. The milk plastic you will make with this project won’t be exactly the same as the old casein plastics, the main difference being a pretty toxic step where you would need to wash and harden the plastic with a formaldehyde solution. That’s not something kid-friendly, soooo crumbly squishy curds it is!
This is a very easy project. All you need is milk, vinegar, and some basic household items.