i know its not a quad build but i built this to help me build my quads hopefully someone finds this usefull , so what i have here is my portable pencil hot air soldering gun ! all you have to do is drill out the metal in the center of black plastic threaded cap so your air tube fits snug as possible for strength & so it dosent move easily , be extra CAREFUL to make sure the metal tube dose not short circut by touching the contacts on the ceramic heating element when you assemble it , also you will need some high temp silicone o rings to keep it air tight at the base of the nozzel i used the tips of the rubberized flume GLO vape pens cut down to size it also matched the red heat protector that came with the soldering iron , then you need to carefully dissasemble the iron to slide the air hose in the back with the power cord to make it look more seamless and you wont need to drill any holes ! dont forget to seal it up air tight with clear sillicone as best as you can because air will leak if you dont ! also put a big strip of 3m clear tape over the buttons and screen to keep it air tight ! ,as you can see the air pump is powered by one D 1.5v battery & i recomend 3v - 5volts for the air pump you can add adjustable voltage regulator to more percisely controll air flow and use slightly bigger air nozzels combos as well , youtube link to it in action !

message me if your interested in purchasing one if you dont want to go through the trouble to make your own ! , ( note : if you want me to add voltage regulator so you can use the pump at 3v-5volts or just add a simple direct connection power plug for a lipo battery Thats an option we can talk about but will effect the price .( note #2 i only posted all the parts so you can see what i used to build it but i have not tested the voltage Regulator or the 18350 cells in the link yet im only running it on 3 AAA batteries but with a regulator you will maintain perfect airflow & be more efficent if you step the voltage down from a 2s battery 18350 pack to 5v with the regulator