I'm pretty sure that I've seen it before, but at Dawn Emerson's workshop earlier this month, I saw this tool again. Not only saw it, but saw it being used.
If you are working on tuning up your color harmonies in your paintings, like I am, allow me to recommend this tool to you. The "Analogous Color Wheel" lets you dial up the main colors in your painting, and shows you which colors complement and are discords. Is you painting mostly blue (as I have dialed in above)? Then orange is the complement and yellow green and red violet can offer some discord pops. Where to get this nifty tool? I bought mine through Dakota Art Pastels here.
And that brings me to a question Casey Klahn threw at me during his recent workshop in town: what would happen if you just turned the color wheel and painted this piece again, but one click to the right or left? I am working on that one.
Do you have a new favorite art tool? Do tell!