Case for Energy Meter Optical Interface Reader

This is an improved case for the optical read/write head for energy meters (smart meters) developed by the ["Volkszähler"](https://wiki.volkszaehler.org/hardware/controllers/ir-schreib-lesekopf) project in Germany.

In addition to the printed parts you'll need:
* a ring shaped neodymium magnet, outer diameter 27mm, inner 16mm, 5mm strong
* a PCB as published on the ["Volkszähler"](https://wiki.volkszaehler.org/hardware/controllers/ir-schreib-lesekopf) project page
* a length of signal wire with 4 strands and and outer diameter of 4mm
* a small zip-tie


I created this design from scratch because the [existing one](https://www.thingiverse.com/thing:3378332) didn't work for me at all, unfortunately.