I added acrylic paint to the mix to colour. I was surprised at how little was needed to colour them so darkly! I might try less for more pastel shades.
The blue one used metallic blue acrylic paint, but you can only detect an occasional particle sparkle. I added some clove powder into the blue one, and you can detect the clove smell slightly, but at the moment as fresh of a cast it is, the vinegary smell overpowers it.
Similarly, I used vanilla powder as an additive in the green one, and it does smell faintly of it.
We'll see how these scented ones balance out in smell after the acetic acide dissipates over time.
I've had good results coloring oogoo with cheap oil paints from Walmart.
(dirt cheap set of oils)
I use a very small amount of bottom of the barrel cheap linseed oil paints with similarly good results..I do find the metalics aren't metalic though after mixing with oogoo though..My silver makes the oogoo white no matter how much I add.
Also I add essential oils (vanilla has worked best for me so far) they still smell like vinegar for the first week though.