Hong Kong's notoriously expensive housing makes owning an affordable home a pipe dream for many residents.

A local architect has proposed a novel idea to help alleviate that problem: building stylish micro-apartments inside giant concrete drainage pipes.

James Law's OPod Tube Housing is still just at the conceptual stage, but it's attracted attention as an innovative though untested way to deal with housing shortages.

At 100 square feet (9.3 square meters) the tube houses are not that much smaller than Hong Kong's infamous "cubicle homes" — older apartments subdivided into cramped and squalid living spaces. They're roomier than other types of tenement housing, such as so-called "coffin" and "cage" homes.

Law has only built a prototype to test public interest but has already received inquiries from around the world.