Here are a couple you may like to choose from to try doing yourself. Each has 18 spaces around the outside. There is no need to have 18 tubes of paint to create these outside colours - it can be done with 8 or less placed carefully at the appropriate place around the circle and then mixed together in different ratios to create the secondary colours in between.
There is a link to the jpeg on my website here so you can download and print it onto watercolour paper and paint is with your own paints.
This one was painted using a small palette of two yellows (Quinacridone Gold and Hansa Yellow Medium), Phthalo Green, Two blues (Phthalo Blue GS and Ultramarine) and three reds (Quinacridone Rose, Pyrrol Crimson and Pyrrol Scarlet. The other reds, oranges, purples, green and turquoise around the outside were all painted with these pigments, then the opposite colours mixed together to create the tertiaries through the middle.
|18 colour wheel with 8 mixed opposites creating dozens of neutrals.|
|Template for 18 colour wheel with 8 mixed opposites|
Here is the template for the wheel above - it has 18 colours around the outside and space to mix 8 tertiaries through the middle section.
|Template for 18 colour wheel with 6 mixed opposites|
This version is a little simpler as it has less spaces for the opposite mixtures through the middle.
To print this one click here.