Download ParticleDraw, to draw with dynamic particles
ParticleDraw is a free drawing program with a simulation engine.
The brushes are dynamic systems of particles with interesting behaviours, which you can customise. Each brush is intricately tuneable with many underlying physical parameters and one can construct arbitrary systems of particles and use these as brushes.
The program has been implemented using the new algorithmic conceptualisation of SMN that is logically equivalent to an SCSPL operating within a self-excited circuit.