Designed by Geoge Hart, published 2017.
(Printed on a Monoprice Mini V1 3D printer, from Thingiverse thing 2132796, 2019,
PLA plastic, 2" square)

Two pieces flow together to form a cube:



Further Reading
Helix Cube Thingiverse Page, from: http://www.thingiverse.com/thing:2132796