I bought these based on reviews, but they were kind of a waste of money. When they work, they're great. However, the paint inside is corrosive and eats through plastic and acrylic which limits what I can do with them. The pens themselves don't flow well, I had to resort to dumping the paint on a plate and dipping the pen in, quill and ink style. A few pens randomly lost the tip and dumped paint all over my project, which was a real bummer. I definitely won't be buying again.