To connect components with each other, gluing is preferred today instead of welding, riveting or using screws. That makes cars, planes and agricultural machines lighter. The requirements placed on the adhesive are high, though: it has to be flexible enough to compensate for stress peaks in the joint zone while still providing a rigid connection in the surface. Fraunhofer researchers have now developed the adhesive “MetAK,” which can be hard and soft at the same time.