Hi,
as a part of the d-diot project, today I have finished this DIY MySensors node that works very well with Home Assistant.
It is Gas sensors based on Arduino with the MQ2 module and integrates a Neopixel RGB led ring plus a buzzer for sound and visual alarms.
This is how it looks:
The case is 3d-printable and the design files are available in Thingiverse.
If someone is interested in the dedicated wiki page you can find a detailed guide to build it from scratch.