I Noticed my Reprap Huxleys hot end fan was vibrating quite a lot, and i was getting wavy lines in my prints. I couldn't completely tighten my fan to the cooling block because some of the heat sink fins got caught in the fan, causing these vibrations. This was an easy fix, just loosen the screws, but this meant the heat sink didn't make a good contact with the aluminium cooling block. So i made this 2mm thick anti-noise frame for the 40mm fan, not only does it kill the noise but also lets me tighten the screws. Oh and this is my first Thing :)Just print it out and sandwich it between your fan and heat sink.