About this 3D model

To place a thin, tall and fairly heavy weight above the sweeper, so that its centre of gravity is on the sweeper itself. ( This design works, however, I find easier to use the design below, with coins as weight: http://www.thingiverse.com/thing:124833 ) This vertical weight design can work with a metal bar, for example. 30 to 60 grams are adequate (the hard-disk in the photo is likely too much weight). For the vertical design idea: thanks to Bas, from the B9C forum. Feel free to message me with suggestions for improvement.