This article was originally published by Metropolis Magazine as "The Enduring Lives of Saša Machtig's Modular Creations."

Even in relative old age, the Kiosk K67—a shape-shifting system of modular fiberglass structures—keeps active. A kiosk in Kromberk, Slovenia, in the former Yugoslavia has become a beehive. Another, used by a Bosnia and Herzegovina food vendor, has received a masonry addition. In Ljubljana, a kiosk that formerly sheltered parking lot attendants now supports an automated ticket machine.

These may not have been adaptations the Slovenian designer Saša J. Mächtig had in mind when he first conceived the K67 50 years ago. But accounting for all of them would have been impossible. In theory, the system permitted unlimited configurations and variations. By the time production stopped in 1999, around 7,500 units of the K67 had been manufactured. While most remained in Yugoslavia, some were exported abroad—among other places, to Poland, Japan, New Zealand, Kenya, Iraq, the former Soviet Union, and the United States. Around the world, they were adapted to uses ranging from border patrol stations and ski lift ticket booths to retail and fast-food stands. No one is really sure how many are still in use today, or what other kinds of folksy, improvised alterations have been made to them, but among the greatest pleasures of the kiosks is their endless capacity to surprise. The K67, a recent retrospective of Mächtig’s work at the Museum of Architecture and Design in Ljubljana managed to restore its original brilliance. And it did so without suppressing the deviations. As the show’s curator Maja Vardjan writes in her catalogue essay, what distinguishes the K67 is “its position between architecture and industrial design, embeddedness in the framework of a modern city and society, the rituals of daily life, and, last but not least, its persistent capacity to reinvent itself.” While the visionary architectural schemes of the 1960s and 1970s may inspire wistful longing (What could have been!), the K67 kiosks, even as they disappear from view, provoke a question: Why have they persisted for so long?