Color: From Hex codes to Eyeballs
I've been trying to build my own mental model that's easy to  visualize how your eyes build color.Imagine 3 people (r,g,b) standing across from each other playing a 3 way tug of war with a bowling ball in the center. They each can feed on certain ranges of radiation to help them pull the ball towards them, color is determined by where the ball ends up. If red and green pull equally the ball moves sideways out of the center to land on yellow.Now take it one step further. The ball actually starts out in a deep pit, if everyones only pulling a little bit the ball lifts up but stays in the center, you have dark grey, if everyones pulling at their max, you get white. What seemed like a flat plane tug of war is actually a 3 dimensional cone.Now take it one step further. The retina is typically composed of 95% red and green cells of various mixtures, and only 5% blue. That means the blue person has a very short rope to work with compared to the others and is not able to move the bowling ball into as many unique positions as the others.If you are red green colorblind then you only have 2 people playing tug of war. Your color model is now 2 dimensional. If you have tetrachromacy you have another person playing and capable of placing the bowling ball into positions not possible with just 3 people. Additionally there is no such thing as pure green, because all radiation that green feeds on will also feed either red or blue as well.edit/ I forgot to add the rod cells, they are another "one step further". They are one extra person but they stand directly over the bowling ball, only capable of pulling upwards, but they are very weak and can't lift it very high.