The bike muffler attaches next to the back wheel. Angle the muffler so the cog wheel touches the rubber of the bike tire. When the bike is in motion it spins the rod making a motor sound. The card inside the muffler strikes a screw and makes a clicking sound. Similar to how a playing card and a clothes pin use to be used, but with the added bonus of a cool muffler. This design is completely printable with the exception of a couple screws. Version two of this design will accommodate the use of a 20 oz. pop bottle as an alternative to printing the entire muffler out. This design will need some glue and screws to bond everything together. NOTE: This design hasn't been test printed yet. I am in the process of running a test print tonight, it should be done by noon Friday (7-1-16). I am using Bike_MufflerV2.stl as my test print file. The print will take about 12hrs to print everything. Printing has begun, I included a couple images of the beginning of the print. I am using a Lulzbot Taz 5 from our local Maker Space to print these, so I have a large print bed to work with. Hopefully all goes well and I can post photos of the printed muffler.