Sony-branded battery based on NiMH technology with a capacity of around 500 mAH. After carefully measuring the dimensions of this battery, it was replicated in plastic with a 3D printer.

[leadacid44] did just that back in 2009, in his case the gadget in question was a Sony Dream Machine ICF-CL75iP. It’s an alarm clock radio, albeit a very fancy one featuring an iPod dock ...