In 2012 I made them into a book, 'Watercolour Mixing Charts', and published them on Blurb.com. Later I also made the eBook available. The First edition is still available through the Apple Store.
In 2015 I spent may hours cleaning up the charts further on photoshop, and re-publishing the second edition. I have numbered all the charts for greater ease of use. This is now available as a hardcover book, a softcover book and an eBook on Blurb.com. The eBook works on the Mac platform so will load into iBooks on your Mac computer, iPhone or iPad. If you have the Windows platform you can now but the book as a PDF. Here is a link to all the second edition versions. You can see a preview of the whole book.
I a considering adding a Premium Lustre paper hardcover option as well.
Here is the eBook link.
March 2015 update: I have just published another book, 'The Ultimate Mixing Palette, a World of Colours', which covers the amazing range of mixes you can get with just 15 colours. It shows every possible two colour combination with the 15 colours that make up my 'Ultimate Mixing Set' and the most useful three colour mixes. You can see all versions of both books here, and link to the website page about this palette and book here.
Then I have a few other book ideas on the go :-)