Engineered heart tissue grafts are created using a scaffold-free, 3D-printing method, then stretched after mounting onto polydimethylsiloxane molds. (a) Human-induced pluripotent stem cell derived cardiomyocytes, cardiac fibroblasts, and human umbilical vein endothelial cells were combined in a ratio of 70%:15%:15% and incubated for 3 days to form cell spheroids. The spheroids are placed onto a stainless steel needle array using a vacuum operated 3D tissue printer, and allowed to culture for 3 days to allow for tissue fusion prior to removal from the stainless steel needle array. (b) Polydimethylsiloxane is cured around a plastic master to form a mold. After the mold is sterilized, stretched tissues are mounted onto the mold while unstretched tissues are allowed to culture free floating in media [Colour figure can be viewed at wileyonlinelibrary.com]