A variety of items make from plastic as demonstration objects

1 cup of milk

Stovetop and pan or microwave and microwaveable container

Thermos or another insulated container

Heat- resistant cup or mug

4 tsp white vinegar

Paper towels


Optional: Food coloring, glitter, and markers

Pre experiment discussion:

Obtain random plastic items and discuss how all of these objects are made of plastic.  Most plastics are made from synthetic chemicals with materials that do not occur in nature. Ask your young scientist if they think plastic could instead be made using natural ingredients.


  1. Add 4 tsp of white vinegar to heat resistant mug
  2. Heat up 1 cup of milk until steaming
    1. Optional: Pour the hot milk into a thermos (for children to preform the next step)
  3. Add hot milk to the mug with the vinegar
    1. Milk should form white clumps (curds)
  4. Mix the mug of hot milk and vinegar slowly with a spoon for a few seconds
  5. Once the milk and vinegar mixture has cooled a bit, use the spoon to scoop out all the curds.
    1. Tilt the spoon against the inside of the mug to let the excess liquid drain out while retaining the curd in the spoon.
  6. Collect as many curds as possible and drop them on top of a stack of two paper towels
  7. Fold the sides of the paper towels and press down on the curds to absorb excess liquid.
    1. Two more paper towels can be pressed Down on top of the curds to soak up any remaining liquid
  8. Kneed all the curds into a ball of dough
  9. *Within the hour of making the dough, add the optional glitter, food coloring etc.
  10. Kneed the dough well before shaping it.
  11. Sculpt the dough with by hand or with cookie cutters
  12. Let dry for at least 48 hours.
    1. The dried casein plastic should be hard.
    2. Drying times cary depending on the thickness of the final item
  13. Once dried, paint or color your item with markers!