I love rainbows, and I love a color wheel.
So you can imagine I was super excited when I found this puzzle!
I ran into it completely by accident at my local WalMart.
It's a wonderful way to teach the color wheel in a tactile way.
Also good for teaching the names of some of the more complex colors (chartreuse, for example)
I'm sorry that I can't find a link to it anywhere, but it was in the toy section of WalMart for about $14.
The pieces interchange, so my kids have had fun not only constructing a "proper" color wheel but also creating designs and flowers and such.