This is basically a MIG welding spoolgun equivalent for plastic filament. It uses 1.75mm 3D printer filament of almost any variety. If you put EVA filament (or some of the more sticky TPU filaments) then it is basically an overpowered industrial hot glue gun that runs all day long without having to keep reloading glue sticks. Otherwise, you can weld together plastic parts using the same kind of plastic that they are made from. If you 3D print, this can fuse together your parts out of the very same filament they printed out of. It operates from DeWalt 20V battery power or a 24V power supply; there are two handle variants you can print depending on how you want to power it. 

More info and instructions at https://github.com/strantor/skeeter

(pretty important to check it out; you won't be able to run the tool without the firmware)