This seems to be my recurring theme - reading the title and misinterpreting the meaning, as times have changed. The first thought I had is that we have some me

This seems to be my recurring theme - reading the title and misinterpreting the meaning, as times have changed. The first thought I had is that we have some metal-can germanium diodes [0] where I clip the top off, and make them photo responsive. This was a practice in the 70s and 80s, mostly with metal-can transistors, but it worked with various diodes too. The packaging was tiny metal can (aka cap), with the lid (aka baseplate) providing the support for the germanium and leads. If the can was removed, often the level of light can impact the gate's ability to transmit current. A real quick way to get yourself a photo-diode when it was in short supply. [0]: https://duckduckgo.com/?t=ffab&q=metal+can+diode&iax=images&ia=images https://duckduckgo.com/?t=ffab&q=metal+can+diode&iax=images&...