A well-maintained shopping cart can last a decade before it's worn out and no longer serviceable. But it can still be useful if it's repurposed. Designer Xavier Degueldre remade several into chairs. You can view more photos of them at Design Boom.
Degueldre added padded seats to some of the chairs, which is no doubt more comfortable than bare metal. But it can be useful to have uncomfortable chairs, as they can encourage guests to leave more expeditiously.