Applying mechanical forces on Drosophila tissues in vivo using the StretchCo, a 3Dprintable device

Applying mechanical forces to tissues helps to understand morphogenesis and homeostasis. Additionally, recording the dynamics of living tissues under mechanical constraints is needed to explore tissue biomechanics. Here, we present a protocol to 3D -print a StretchCo device and use it to apply uniaxial mechanical stress on the Drosophila pupal dorsal thorax epithelium. We describe steps for 3D printing, polydimethylsiloxane (PDMS) strip cutting, and glue preparation. We detail procedures for PDMS strip mounting, tissue compaction, and live imaging upon force application. For additional details on the use and execution of this protocol, please refer to Cachoux et al. (2023)1 from which the StretchCo machine has been derived.