getting a ferrite part is going to be hard for shielding especially shaped like a propeller and even ferrites are still got some attraction to magnets so it would effect its spin in the long run and if the shielding isent good the neodymium magnets pull on the motor would effect it if its got internal magnets or iron core type motor
I made something similar to ferrite one time to see if it would work. Just mix some epoxy resin with catalyst and some iron powder and put it into a custom made mold. It worked. It would conduct magnetic fields without inducing eddy currents in the custom made part.