The open cup technique creates fascinating color gradients. Normally, you take a cup, cut off the bottom and pour the paint into the open cup from above. The paint now emerges from under the cup and mixes there, creating the color gradients and often very beautiful cell formations.
In this version in the video, I haven’t turned the cup upside down, just removed the inner circle of the cup. What remains is a wider edge that mixes the color in a completely different way.