When the tenon swells in the moist tropical air, it creates a tight joint. Glue makes the joint even stronger, but Eckelman says it isn't necessary. Meanwhile, Haviarova used Eckelman's joint design as she sought out and created wooden test furniture from native Costa Rican wood species. We made use of what would otherwise be waste material. We tested thinnings from timber plantations and unusable pieces from pallet decking.
Local schools can get similar wood at reasonable prices.
Haviarova designed laminated wood, solid wood and bent wood furniture using simple equipment that is readily available in developing countries. Then she tested her designs using methods developed by the American Library Association, and her furniture designs and Eckelman's joints more than passed. They'll build furniture locally and use it there.