Size, shapes, colors, and opacity of the brush will be changing randomly.
When you hit the button first time, the shape will stop changing.
After the second hit, it will get smaller or bigger with fluctuating again.
The range of brush size is set between 50 and 500. The brush change rate (fRate) is 15Hz.
You can draw with only one shape by turning off the random option (rShape) on the source.
Enjoy this with modifying variables as much as you can.

Source code: RandomBrushDrawing

Built with Processing