I keep reading about using oil based pens on nonporous surfaces. The difficulty with these is that they are usually those paint pens that you need to shake and prime to get to work. And, the points are rather broad. I just didn't like them for much of the tangling I wanted to do.
But then... I found Uni Pi:s. They are double pointed oil based markers that were very easy to use on this child sized tea set. I cured the pieces in my oven after I tangled them and am very pleased. The Uni Pi:s come in 12 colors, all vibrant and consistent in flow. They are going to be my favorites for nonporous surfaces. You can find them at Jet Pens.