
Particle Zookeeper, Julie Peasley hand-makes the particle plushies in her studio in Los Angeles. Her "particles are art items factoring the equation: SCIENCE+ART=UNDERSTANDING." In addition to being doggone cute, Peasley creates her plushies to raise awareness and interest in the fascinating field of particle physics.
To simulate maximum mass - she adds gravel to the dark matter (instead of standard poly-fill minimum mass)

The Particle Zoo: Sewing the fabric of spacetime
http://www.particlezoo.net/