Two things about this story are amazing: that something so seemingly simple hasn't been developed before and that something so seemingly simple still took a lot of work to, well, make simple.

British industrial designer Martin Riddiford has created a pineapple-size lamp powered by a 25-pound weight that falls about six feet in a half-hour. That may not sound like much, but it’s enough to drive a silent motor at thousands of rotations per second. The GravityLight, which shines slightly brighter than most kerosene lamps, requires a certain amount of elbow grease: Once the weight reaches bottom, it must be manually lifted to repeat the process.

Riddiford, 57, a co-founder of London-based product design firm Therefore, got the idea four years ago after leaving a meeting with a charity interested in solar tech. “I just sort of had this vision of, well, why can’t you use human power and store it as potential energy rather than in a battery,” he says. The designer, whose Brinlock Abacus calculator was the first with number-shaped buttons, and whose firm has developed products for Toshiba, Samsonite, and Nike (NKE), says he regrets not having done charitable work overseas in his youth and hopes to make up for it with his light. The first prototype, a large-scale contraption involving a bicycle wheel and a windup LED flashlight, was refined over four years into its current cheap yet durable plastic version. “It’s technically quite tricky to get it so it doesn’t jam, but we solved that problem through lots of experimentation,” Riddiford says.