James Gurney has been a great teacher to me through his blog and videos.
This posting of his (and his friends' ) started me on an amazing journey of my own, only a few months ago:
I started with a plain Altoids tin and a cut-up plastic container of pan watercolors that came with a beginner art set someone gave me. An eraser and sharpener and tissue will fit in on top of the little plastic cover for the watercolors. The real benefit of using a tin (instead of a plastic cotton swab holder for example) is being able to attach it to your sketch pad with a magnetic clip ("chip clip").
Below is another great link that illustrates exactly how to make your own kit. I will probably use the magnetized half pan idea, as long as it doesn't get too heavy, so that the colors are individually and easily replaceable. "Tacky" material doesn't really hold them very securely and it's not fun when they fall out. I like the idea of using small Yuba paper inserts as palettes (not sure where I saw that) in addition to painting the lid white.
Then, ta-dah! at Bass Pro Shops. It's meant to hold a gift card and cost about $4 I think. The "handle" works great as a finger ring if I want to hold it instead of clipping to the sketch pad. It's slightly taller than the Altoids and will hold a little more "stuff", but is still completely portable.
And a magnet dropped into the little water bottle holds that in place too. I think I prefer having my paper to the left as I am right handed, so my sketch books will be Asian, I guess!
Waterbrushes are an absolute must! Recently I started using one filled with waterproof black ink, with good results (another Gurney idea). I put together this little brush holder, though, because sometimes I want more control and choices. Can't remember where this idea came from, but the rubber band is the key to keep the brushes from shifting and smashing the hairs.
Brushes held by rubber band to cut up plastic pencil holder insert taped to cardboard within small pencil tin. I cut the corners back so I could easily pull the brush holder out of the tin.
Since then, my "kit" has expanded to 2 diaper bags full of stuff, including some purchased kits. Sounds like a George Carlin routine! But that's another story!
So, a long post for me on an evolving subject...but this kind of sharing from others brought painting back into my life!