Is your MK4 sitting unused and lonely since you\'ve upgraded to the MK5? Give it a new lease on life and turn it into a handheld welding gun! Use it to patch up any holes or loose threads in your prints or to glue broken plastic parts back together. You can see me welding the lid of a very poorly printed and particularly dangerous teapot shut to prevent accidental use.The STL files include parts for a hand grip that slips over the DC motor, a finger guard so you don\'t burn yourself on the retainer washer, and a trigger bracket for a push button. SolidWorks 2010 model files are also included.Assembly Instructions:Usage:Open up the control panel in ReplicatorG and set the temperature to 220C. When the nozzle is at the right temperature, set the motor PWM to 255 and select \'forward\'. The motor will not turn until you push the trigger button, allowing you to control the extrusion manually. Be careful not to operate the motor until the nozzle is fully heated up, otherwise the filament may strip or the nozzle may break!