This tray is from a child's set of watercolors from Target or Michael's.
They cost about $5.
The paints are pale and waxy, but the lid has little dimples for mixing, and I put good quality tube watercolors into them.
It doesn't leave any room for mixing paint.
I think professionals use a limited palette, and/or they know what colors they will need.
But I like having all the colors out at once!
I painted some flowers Friday:
Yesterday I scribbled with a wax pencil made for filling in chips in wood furniture.
Then I splashed paint and ink on it:
I did another one today: