https://www.instructables.com/id/LoRa-Tooth-Small-Wireless-Sensors/
**Parts!**
* SPDT reed switches: https://uk.farnell.com/hamlin/59140-030/magnetic-sensor/dp/1383368?st=magnetic%20switch
* SPDT magnets: https://uk.farnell.com/littelfuse/57140-000/magnetic-sensor/dp/1526531?MER=sy-me-pd-mi-acce&st=magnetic%20switch
* Battery holder: https://uk.farnell.com/renata/smtu-2032-lf/holder-smd-battery-for-cr-2032/dp/1216354?st=cr2032%20holder
* Battery: https://uk.farnell.com/varta/6032101501/cell-lithium-cr2032-230mah-3v/dp/300445?st=cr2032
* Boxes? https://uk.farnell.com/hammond/1551v1wh/enclosure-small-abs-white/dp/2985866