Nearly 30 pounds of old crayons from all over the country land on Kim Martonosi’s doorstep every day. With the help of her kids, she sorts the worn and broken wax sticks by color, melts the bins of blue-greys and light greens and pinks down to a gooey swirl, and shapes the new creations into stars and earthworms and simple sticks. Over the past 25 years, Martonosi’s business, Crazy Crayons, has salvaged just over 120,000 pounds of colorful wax, the equivalent of about 12 million new coloring tools.