Input: blue crank.
A pin on violet slider moves along heart-shaped profile of a stationary cam under orange spring force.
The pin center traces a heart-shaped curve (in green).
Point of the green part adjustable fixed to the violet slider traces a heart-shaped curve (in pink) that is the equidistant curve of the green heart-shaped one.
The heart-shaped profile of the cam is created from two ellipses (in yellow).The mechanism can be used for cake decoration.