after unhinged metal covers with a plastic core. Here are parts of PMS7003. The metal covers are similar to clamp shell except they dovetail into the plastic board.
fan to pull the air through the chamber where a laser diode (showing in a metal tube) pulses light across the airflow
a complete part of laser diode, photo-detector (photocell, in circle) and chamber to count particle
the circuit showing the customized chip marked as Plantower
close up to the main chip, Plantower PT-DSC0916. Here is another nice dissect
the unit is packed up and still functional