To get started you need to make a pendulum.
I recycled an empty contact solution container because I wanted to be able to quickly and easily stop the flow. I cut off the bottom and reinforced that area with duct tape. Next I drilled three equidistant holes about .5" from the bottom of the bottle. If using a plastic water bottle, a hole puncher will work.
Next loop about 1 yard of string or twine through each hole. Connect the three lengths at the top. I used a tripod we had at home, but you could also place a broom handle across two chairs.
Tempera paint that has been thinned two parts to one part water is added tot he container with the hold plugged. Place paper under the tripod, remove the plug and let it go.