Before the invention of hard plastics, people used milk — Here's how... | 22 Words

With just a little bit of vinegar and a strainer, milk can be turned into a completely moldable putty that will set hard as rock. Before today's variety of plastics came along, this milk-based product was used in the production of buttons, pens, knitting needles, and much more.

Here's how you can make it yourself...

(via Doobybrain)