3D-printable replacement blades for the extruder cooling fan. The cooling fan placed in front of the extruder's heat sink has the important job to keep things cool above the hot end.
By accident and a bit of bad luck the fan blades can break if hit by an object or while changing the filament. It is very important to maintain the cooling function of the fan by replacing the old one with a spare part.
Nevertheless in the spirit of owning a Replicator 3D printer at home we wanted to test if the fan blades can be replaced by 3D printed new ones.
After cutting off the old ones and grinding away the remaining part of the broken ones, the fan barrel becomes a cylindrical shape onto which a flange with new blades can be attached.
After a few minutes with a calliper and CAD software we created a thing flange (0.5 mm) with nine attached blades.  
The design is made to be clamped onto the blade-less motor housing and no glue is required. Our tests turned out successful thus making it possible for one to 3D print new fan…