I cut apart the plastic tray that my ancient Rowney Georgian water colors came in. So now I have a small butcher tray sort of palette, a studio type with wells, plus a flower shaped one that I prepare my washes in.
i'm not actually that fussy so i went for a hybrid between the two. i use old chocolate tin lids, saucers, pallets with wells that clip on to my paint box that have rectangular wells some deeper then others, circular wells, a flower shaped pallet... basically what does the job.
I have three that I switch between depending on the type of watercolours I'm using: inks (round palette with deep wells), tablets (smaller round palette with shallower wells) or tubes Large rectangular palette with round and square wells). I also have a flat palette that a friend gave me, but it doesn't work with the way I use the colours.
I have this plastic palette with square and round wells, but I also have a porcelain tile if I want to be able to mix real quick. I use the plastic thing the most. I never EVER use the lid of my prrrrrecious watercolour-paintbox...