I am making a soldering station (with an arduino as the controller) and would like it to be able to sense if someone is holding it.
I don't really want to use capacitive touch, because then the handle would have to be conductive.
I would like some sort of way to detect if a hand is near the sensor (to give a bit of room for error if holding the iron not directly by the sensor)
A capacitive sensor will work OK through a layer of insulation.
Alternatively you could use an accelerometer as it's difficult (perhaps impossible) to hold anything perfectly still for more than a couple of seconds.