Summary

Micro adjustable prop cutter for 3" props. Use a M5x45 screw and locknut, tighten just enough to to keep the screw from moving. Here it is in action: https://www.instagram.com/p/BsO0pw6Aw7W/

If your slicer doesn't pick up the threads on the small part, check out this remix that embeds a hex nut in it instead.