This diy tool is called an air gun chip guard or chip shield. Some specialty blow guns come with this attachment but mine did not so I decided to make one out of some scrap Lexan polycarbonate. While it is considered a tool for a machinist to use on a lathe or milling machine, I have found it very useful for metalworking, woodworking, and working on small engines and automotive engines. It is a great tool for any workshop to have and it was fun figuring out how to form polycarbonate into this shape.