So what's the current state of the OpenAirMonitor? I've completed the hardware design and schematics, manufactured a rev 1 of the PCB with JLCPCB, and then made the following fixes:

• a floating pin on the LDO that's now grounded
• replaced the LDO with a AZ1117CR2 as the HT7333-A is underpowered.
• I've also changed the STEMMA pins as rev 1's pins are also used for NFC
• moved the PMS7003 connector as it wasn't correctly aligned with the sensor location

I haven't yet ordered a rev 2, as it was easy enough to fix the rev 1 PCBs by replacing the LDO and putting a bodge wire to ground. I also found a way to use pins D9 and D10 on the MDBT42Q module by disabling NFC in the Espruino CLI:

NRF.disconnect();
setTimeout(function() { 
    NRF.restart(function(){ 
        LED.set();poke32(0x4001e504,1);
        while(!peek32(0x4001e400)); // enable flash writing
        poke32(0x1000120c,0xfffffffe);
        while(!peek32(0x4001e400)); // NFC pins as GPIO
        poke32(0x4001e504, 0);while(!peek32(0x4001e400)); // disable flash writing
    });
}, 1000);

 You can check if NFC is enabled on the Espruino module using:

peek32(0x1000120c).toString(16) == "fffffffe"

Right now I'm working on the enclosure design. You can download the OpenSCAD file from Files, but note that it's not quite yet ready for prime time. What still needs to be done:

• adjusting the zip tie holes for holding the battery
• making sure there's enough space for the o-ring in the lid
• making sure there's enough space for the hex nut holes
• checking the solar panel fit