How I Built This with Guy Raz

Springfree Trampoline: Keith Alexander & Steve Holmes

In the late 1980s, a New Zealand engineer named Keith Alexander wanted to buy a trampoline for his kids. After his wife said trampolines were too dangerous, Keith set out to design his own — a safer trampoline, without metal springs. He tinkered with and perfected the design over the course of a decade. But he was daunted by the challenge of bringing his…