Tired of the feeder that wants to detach itself from the ultimaker frame each time you push the filament upwards manually?
Scared that it falls off each time you move your box around?
Just stick this thing in the free space above the extruder arms to lock it in place.
OK the best surely would be not to have to push the filament by hand at all, but at least now I do not need both hands to do so :)
Update 2013 04 28: now customizable for any dimension or fine tuning!
Printed with 0.1mm layers, 0.8mm walls and 35% infill (I think less would still be OK).
The thing is completely parametric, you can tweak or derive something better.