DIY Plastic Toys

Did you know you can make plastic out of milk and vinegar? How cool is that?! These DIY plastic toys are so fun to make and are such a cool science experiment for kids!

For this activity, you will need vinegar, milk, food coloring, a cookie cutter, a bowl, a strainer, a plate, and paper towels.

To create plastic out of milk, pour 1 cup of milk into a microwave safe bowl. Microwave for about 90 seconds. You want the milk hot, but not boiling.

Next, stir in 4 Tablespoons of vinegar. As you stir, you will notice the milk starting to form clumps. Stir for about 1 minute.

Strain the milk through a strainer, pushing on the clumps to squeeze the liquid out. Dump the solids onto a paper towel and use the towel to squeeze more liquid out. At this point, you can add a few drops of food coloring if you want to, kneading it into the solids.

Place a cookie cutter onto a plate and line with a paper towel. Place the solids into a cookie cutter, pressing into the edges and creating a smooth surface. Let the solids dry for 48-72 hours, switching out the paper towel as it gets soaked through.

The shapes will turn into a hard plastic! The boys loved this experiment and have all sorts of ideas for making their own toys!

Now, for the scientific explanation behind why this happened. Milk contains a protein called casein. When you add an acid (vinegar) to the milk, it changes the pH of the milk. The casein molecules react to the acid and unfold to form a long chain, which is seen as the milk curdling. When these molecules are separated from the liquid and dried, they become what is knows as casein plastic. The plastic can then be molded into shapes. Pretty cool!