Still, this topic seems to be controversial, mostly by people who have a bury-your-head-in-the-sand approach to security and safety.Here are the materials:Pipe the same size the air compressor port will use, 16-18 long.Some exhaust pipe, the same length as the other pipe.Some washers you have to make with a hole saw, enough to put one on each end and one every 1-1/2 that will fit around the air