Big Suggestions (both Demo and Full)

[Kubby]

3) Custom Paints are currently not possible, however I do think i'll tweak the colors in the near future. (Less weird colors, more common colors)

Well, regarding colors or more accurately, color selection UI, I'd go for smaller buttons, with relatively more area of each being the color. Also, when you add colors, try to add some pastels, and some less saturated colors, if you could?