Necklace Magnet

I used PLA, but ABS/ASA would be better if this is left outdoors or in a car.

This was designed to work with a TPU filament as the necklace string.
I use needle nose pliers to pull the end through the hole in the side of the cone.
Tie a tight knot close to the end and carefully melt with a lighter to make a fused end. 
Then pull the filament back the way it came until the end is fitted inside the cone area.

I use 10x2.3mm magnets - https://www.amazon.com/SMARTAKE-Refrigerator-Magnets-Multi-Use-Whiteboard/dp/B081GDWRZT

You can resize the negative part from the .3mf file for other magnets.
Just remember to adjust the pause layer as well if you do.