Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:3367776.
My Bostitch impact wrench quit working or rather wouldn't stop working. Whenever I attached the air hose it would immediately start spinning and wouldn't stop. I disassembled the air valve mechanism and discovered that the valve seal deteriorated, some of the plastic coating had chipped away. I had trouble finding a replacement part that didn't come with a bunch of other parts and decided to try and make my own.
IT WORKED! My Impact wrench is back to working like it should. This design was a bit tricky since it's a re-enforced valve seal that uses an M8 washer embedded inside of it.
IMPORTANT: After slicing the model, I uploaded my gcode file to https://www.prusaprinters.org/color-print and told it I wanted to change color at 3.2mm then downloaded my modified file. Remember that the printer will unload the filament and you need to cut it on an angle and reload it. Read the notes in the Print Settings section below for more information on how I prepared the washer to be embedded in the print.