Author : https://www.thingiverse.com/davemakesstuff/designs 
Source : https://www.thingiverse.com/thing:5832925 

Summary

These “Helical Hearts” twist apart into two separate but identical pieces. Print in different colours to highlight the spiral curves.

The “Large Helical Heart” has a hidden compartment for rings or contraband.

See here for video: https://youtu.be/SSzDglASqT4

See here for stable downloads:
Large (plain and with hidden compartment): https://social.thangs.com/m/690383
Small: https://social.thangs.com/m/690164

The “Large Helical Heart” is 80mm at the widest point, the “Small Helical Heart” is 50mm at the widest point.

In order to preserve a smooth sliding contact surface, print the files on the side as they are oriented. Try raising the model off the bed by 3mm or so and building tree support up to the overhangs.