Balancing Spool Mount for Prusa Mendel

You want to connect a filament spool to your Prusa Mendel?
The filament spool will balance on two treaded rods.

This mount is a bit shaky, but so far durable.
Too much load might cause damage. So use it at your own risk.

Update:
The lower structure is not stable enough. At 37°C room temperature and a weight of 2 kg the arms bended. The spool mount broke.
Please upgrade to the new fortified spool mount. http://www.thingiverse.com/thing:29142
Or use far less weight.