Jet turbine extruder indicator

all you need are two 2 by 6mm round neodymium magnets, a drop of glue and a few gramms of fillament ;-) 

Glue the magnets onto the rotor, after putting the spacer around them and put it into the duct. The duct goes on by removing two screws from the extruder motor and putting them back in through the holes in the duct.

Have fun.