This is an idea of a suppressor that you fill with cotton ball or Scott towel (i did this when i was younger with an airsoft and this was acting very well to suppress the compressed air sound) Also provide Solidwork 2015 file to make it fit to yours. Update 26/03/15 Added photo of a fail print, and i'm now in work to switch from 3 mm to 1.75 mm so another try will happen in the next month. Also modified some diameter to fit better on the next version. Update 22/04/2015 Finally receive all my roll, and switched to 1.75mm. Print it, and sand it a little bit to make it press fit (need more calibration). Will try it this weekend, but i'm sure it will suppress at least 50% of the sound.Print the 2 piece (outer and inner) Sand a little bit if it don't fit well. Add some scott towel and roll it over the inner barrel (or anything that like that, toilet paper) Put the outer barrel over and slide it on your barrel.