Abstract
Cryopreservation of coral sperm requires reliable, travel-ready, inexpensive hardware. To this end, we developed and tested a robust, second-generation, conduction-based cryovial cooling rack assembled from 3D-printed and commercially available parts. Cooling rates from −10 to −80 °C were found to be repeatable at −22.9 ± 1.9 (rate ± SD) °C/min for 1-mL samples and −35.4 ± 3.3 °C/min for 0.5-mL samples. This represents an improvement on the variability of cooling rates in an older design, which was found to be −31.8 ± 7.1 °C/min for 1-mL samples. Design files and a manual were produced to encourage widespread use and the development of derivative designs.