Other than the Arduino MKRWAN 1300, the PCB features a L293E chip for stepping up the voltage and current required for the alarm system, which is itself a block of 8 LEDs and 3 buzzer beeper chips. Attempting to run these devices directly off the Arduino would instantly frazzle the device!

After assembly and testing, the whole thing worked perfectly and, after a bit of experimentation, the best resister for the red LEDs was 39 Ohms.

Although most of the components are surface mount, they are all very large and no stencil is required. After checking the polarity of the LEDs, the PCB was pasted up with solder, populated with the surface mount components and chucked in the toaster oven for cooking to 260 degrees C.