This little accessory fills in the hole under the nozzle. The purpose is to allow the filament to go down vertically without friction avoiding to stop in the corners of the laser cut wood plate.
After you print it, you have to take a little piece (5mm) of 3mm PTFE tube and cut it longitudinally. After paste it with silicone glue. This is a good solution for who doesn't want or cannot fix the Filastruder on a wall and need to have a smooth vertical descent. You can find here the STL file:

http://www.thingiverse.com/thing:1348283