Homemade Zigbee buttons made from Sonoff door/window sensor circuit board plus 5V/3V PSU and push-button switch : r/homeautomation
DIY zigbee devices
Aubess Zigbee Tuya Smart Temperature And Humidity Sensor Diy Smart Scene Smart Life Remote Control For Alexa Google Assistant - Automation Modules - AliExpress
Build Your Own Universal Zigbee Logic Sensor - Gadget-Freakz.com
Sonoff Door Sensor Automation | Door Window Sensor Sonoff - Snzb-04 Zigbee Smart Door - Aliexpress