Use the variable at the bottom of the screen to choose one of the following color spaces to work in: RYB (red, yellow and blue) RGB (red, green and blue) CMY (cyan, magenta yellow) Use the variables at the top, to choose how much of each color goes in to the rainbow (what the 3 colors are depend on the chosen color space)
I got inspired by above's project https://scratch.mit.edu/projects/56300532/ and thought I'd combine it with my RYB color picker https://scratch.mit.edu/projects/64912702/