B9C sweeper weight - vertical v07

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.