I made one myself at home ,
i think it works not bad ,
material = plastic bottle , gas hose < i'am using 9mm transparent type > and sponge like thing that you often get when buying delicate items like computer...
http://www.bmwclubmalaysia.com/wp-content/uploads/2007/09/abc37918.jpg
BMW 3-series coupes powered by the M V10 seem to be the flavor of the month with no less than three different models from three different tuners...