Nonspherical snowman-shaped micro-sized particles were synthesized via monomer swelling and the polymerization of crosslinked seed particles. Monodispersed crosslinked polystyrene microspheres and methylmethacrylate were used as seed particles and the swelling monomer, respectively. Methylmethacrylate (MMA) induced crosslinked polystyrene microparticle swelling; however, compared to polystyrene, MMA is relatively hydrophilic. As a result, phase separation was observed, resulting in monomer-swollen, cross-linked particles protruding from the surface of the seed particles. By changing the monomer-to-particle weight ratio from 4 to 8, the ratio of the size of the head to the body of the snowman-shaped particles was varied from 0.3 to 0.7. The morphologies of the snowman-shaped particles were predicted using Surface Evolver software, and the simulation was applied to show the unique self-organization morphologies of snowman-shaped particles. [GRAPHICS] . We synthesized snowman-shaped microparticles by swelling and polymerizing cross-linked PS seed particles with methylmethacrylate. The monomer-swollen, cross-linked particles exhibited protrusions from the surface of the microparticles due to the phase separation of seeds from the particles. The size of the protrusion or head of the snowman-shaped particles was controlled by changing the monomer-to-particle weight ratio during the swelling process. Simulations were applied to estimate the aspect ratio of snowman-shaped particles and their self-assembled morphologies.