First, I want to thank RRacer and traviz the original author for his excellent work, we can find it on cults3D and thingiverse.
His information:
Designed mount and screw holes. Holder and middle part have 2x 5.2mm wholes. Top part has 2x 4.5mm with bigger walls around to increase strenght. Top surface is flat without any holes visible.
Material used:
1x Xiaomi Aqara sensor / 1x Sonoff SNZB-02 sensor
1x top part
3x middle part
1x holder part
2x 5x60 screws
TIP: set seam position to be at the back so it wouldn't be visible.