Picture: A one-of-a-kind 3D printer built at the University of Minnesota can print touch sensors directly on a model hand. Credit: Shuang-Zhuang Guo and Michael McAlpine, University of Minnesota, "3D Printed Stretchable Tactile Sensors," Advanced Materials. 2017. Copyright Wiley-VCH Verlag GmbH & Co. KGaA.