Lockring with M3 Nut

A remix of a remix. Working from original thing https://www.thingiverse.com/thing:4645955 I needed the locknut to be M3. Someone already created this, but the dimensions were fractionally off. This remix has proper sizing for an M3 nut. Note: Add a pause in your printing just before the middle starts to close. For me this was Layer 21, or 4.20mm