Kevin has a good review of Mr. McGroovy’s cardboard box rivets, he writes -
“Cardboard is a wonderful building material. You can do far more with it than you might expect. Use it to make furniture, sculpture, models, and of course play structures. The common way to assemble projects with cardboard boxes is to slap pieces together with duct tape. But tape is clumsy, expensive, will unpeel outdoors in weather, looks clunky, and won’t take paint. A cool alternative are these Kevlar-like rivets specially designed for box cardboard.” – Link.