A simple inexpensive cryogenic storage device for microscopy specimens

Cryogenic storage devices for microscopy specimens are costly and may require a particular size or type of dewar. Described here is a simple inexpensive storage container for small specimens (less than 5 mm in diameter) which can be constructed in less than 15 min from common laboratory materials. The unit is modular in design, can fit into any thermos type dewar and is reusable.