Almost Impossible Heart
Fabricated on a 3D printer by L. Milekic 2016,
from a 3D print design by G. Frost,
posted in 2012 on the web page
(PLA plastic, 2" x 2" x 1.5" thick)
The two white pieces are the same shape but are not quite the same dimensions.
for the two dark pieces
(that are symmetric to the white pieces).
So first match each white with its corresponding dark piece.
The two white pieces slide together on one plane and the two dark pieces slide together on a perpendicular plane.
Start by putting three together and see how the fourth fits in.
Then spread them all apart just right with the fourth piece now in position,
and push together with simultaneous movement.
Takes a bit of dexterity.