Amazon.com: Battery-Biz Inc. 3 Volt Lithium Battery : Automotive
Found a Minox 35 GT in super good condition (just needs a good clean). I adapted the battery compartment to use 4 LR44 cells, that are about the same size of the
Minox E GTE GT E Miniature Camera with Minoxar 1: 2.8 35 mm Optic: Amazon.de: Electronics & Photo