This is a prop spinner cone for the Syma X8 series quadcopter, or any other 3mm shaft. Photo is shown next to the original (chrome) spinner cone.
Update: v2 STLs are modified slightly to allow better clearance for the prop clamping mechanism.
Printed in PLA and PETg with 3 perimeters. Sliced with S3D.
Designed in Autodesk Fusion 360