Hi there,
This is Bogdan from Romania.
I'm a mechanical engineer - specialized in the industrial robotic field, 3D designer and modeler (from time to time and some projects I could make the functional prototype too).
I'm doing product design, industrial design, reverse engineering, ideation, etc.
I have over 15 years experience working on various systems/devices across multiple industries, from concept to launch.
1 - the trick here will be to get designed the melting head which to behave properly with 7-18VDC instead of 110/220VAC. this will mean an increase of the current in order to achieve the same power (depending on the silicone stick diameter, the power of the gun ranges from 20 to 200W)
2 - one good option, but more expensive, is to use LiFePo4 batteries/accumulators which provides a higher current density
3 - the handle of the gun could be designed to accommodate even a fixed battery or an interchangeable one, and this could open the way to use an existing battery (from a cordless power tool, ex. screwdriver, grinder, drilling machine, etc) which will make the prototype easier to be built
we could discuss all the details here...
Regards
Bogdan