Color magic: mixing made easy

We have been updating a bedroom into a studio space in slow motion over the past year, and this past week Danielle installed beautiful hardwood floors. There were a few places that needed wood filler, and it stood out in contrast the rest of the flooring color. Now, I don't know if this is the right way to deal with this issue – flooring and construction are not my things – but I figured I could just paint the filler with a thin layer of acrylic paint before we did the finish, and see if I could make those lines disappear.

Here's some practice that I did. We put two smears of filler (that light stuff) on a cutoff piece of board. The one on the left I left for reference, the one on the right I tried to color with paint. It's not perfect, but it was just practice.

Mixing an exact color like this is actually a pretty simple process. I think of it as moving a color mix through a maze. At any given time, there are 4 kinds of colors we can add, which takes us in 7 directions: