But so much travel takes its toll, and eventually the containers wear out and are retired. That’s when architects and designers, especially those with a “green” bent, step in to turn these cast-off boxes into student housing in Amsterdam, artists’ studios, emergency shelters, health clinics, office buildings.

Despite an oft-reported glut of unused cargo containers lying idle around U.S. ports and ship yards – estimates have ranged from 700,000 to 2 million – the Intermodal Steel Building Units and Container Homes Association puts the number closer to 12,000, including what’s sold on Craigslist and eBay.

HyBrid Architecture in Seattle, which has built cottages and office buildings from containers for close to a decade, coined the term ” cargotecture” to describe this method of building. Co-founder Joel Egan warns that although containers can be bought for as little as $2,500, they shouldn’t be seen as a low-cost housing solution. “Ninety-five percent of the cost still remains,” he says.