This entry into the foam heater challenge was driven mainly by simplicity and usability.
The nozzle itself is completely sealed and removable by simply unscrewing the nozzle from the foam gun.
The heating is done via a heating-foil type part. The heating coil is made out of 0.5-0.75mm thick Nickle Chromium resistance alloy(takistustraat) and covered on both sides with Kapton film(heat and electrical resistance tape). Because the heating coil wraps around the whole nozzle and distributes energy efficiently, it can be very slim and slender.
The heating coil can be heated and controlled by a small 230v to 5/12v adapter(just a few ampers is needed to heat the coil, so a phone recharger is sufficient).
This makes it extremely simple to manufacture even in small production runs and is very safe.
The nozzle cover piece(green) can be made out of aluminium(specific heat between 1300-1500) or Nylon/polyamide(1700-1750).