As 14-year-old Sarah Buckel finished her last year at Central Catholic Middle School in Du Bois, Pa., and was taking down her locker decorations, she wondered whether there was an alternative to scraping adhesive and tape residue off the inside of her locker. She had an idea.

She also had a father who was chief operating officer at MagnaCard, which makes magnetic business products. She asked him to make magnetic wallpaper for her. The invention stuck. Soon the decorations were patented and sold at Target, Rite Aid and Staples, making $1 million in sales the first year. Her dad bought MagnaCard, where she’s now a graphic designer at age 24.