I saw this idea a while back when I was looking through other wonderful Blogs( I can't remember where I saw this or I would give proper credit), this was a great idea so I had to go out and get some clothespins!
I use sponges for any kind of shading on projects and I used one triangle piece for multiple of colors and always had to remember which color was on it, or I would try to find an empty spot on that piece and add more color to it lol .
So here is an easy solution..
Cut off a triangle piece and clip it to the clothespin, once you are done using that specific color I take the coordinating marker and color one side of it and write the name of the color on it with the Journal marker.(this also saves getting all that ink on your fingers when applying shading)
I have this cute little Card stand that I keep on my crafting table, and now it is being used for cards on the top and clothespins on the bottom.