All the 3D designs and tips on printing them are available in the Supplementary Material. After 3D printing, the molds were washed for 10 mins in isopropanol in the Prusa wash-and-cure machine (CW1S), washed with fresh isopropanol, and dried using airflow. The parts were then post-cured using 2 mins at 37 °C and 10 mins under UV light using the Prusa wash-and-cure machine (CW1S). Using this wash-and-cure method, it was unnecessary to coat the 3Dprinted part to peel off the PDMS after curing.