So, why do you want to make a colour-wheel, how does it work, and how can you make one out of lego yourself?
Personally I’ve had a too strong tendency to consider colours as a linear scale, usually from red to purple (which may be because I’ve gotten used to stacking bricks).
Although rainbow-scales are pretty to look at and good for analogous colourschemes made out of bright colours (like yellow-orange-red), they won’t help you if you wish to work with the much more effectful contrasting colourschemes (or understanding more complex colours such as tan: yellow, orange, and a pinch of blue or dark red: red with pinches of yellow and blue).
Picture time! Here’s the colour-wheel I made just after returning home for the weekend:
 
Contrasting colours are the ones sitting opposite eachother, like red/green, yellow/orange etc. An interesting fact is that if you mix up all primary colours you’ll get brownish colours - if it’s possible to consider a colourscheme as a “unified” colour, this may explain why “rainbow-warrior”-schemes are generally frowned upon - because it ends up messy or muddy.
The colour-wheel might help you create the much talked about 3-colour-scheme, if you consider each of the primary colours as primary, secondary and accent (I haven’t actually tested this yet, but I’m fairly sure it should work pretty well).
Enough talk for today, here’s the reverse of my colour-wheel so you can build one yourself:
 
Ah well, a little more ;)Â - tertiary colours are named after the primary colour and secondary colour next to it - ie. yellow-orange, for instance, is the one between yellow and orange.
I’ve used the following lego-colours for tertiary colours (counter clockwise): acid green (yellow-green), teal (blue-green), royal blue (blue-purple), light purple (red-purple) and earth orange (red-orange), and light orange (yellow-orange).
I’m definitly not satisfied with the royal blue (colour seem ok, but it’s too light) and earth orange (too muddy: must have some blue in there) - If you have any better suggestions, I’d love to see a picture.