What kind of paint marker will work for flexible vinyl? I'm making a mini cape out of flexible vinyl, like the kind used for window clings. I need to leave light blue, permanent marks on the vinyl that won't peel or flake as the cape is flexed.

I'd really prefer a pen or marker of some kind, because I need to make designs that I am not confident I can do with a brush. The designs also need to be quite fine, like 2-3 mm max. 

Is there a single type product that would work? Or would I need to use multiple products (application + sealant?). I have no idea what will actually adhere to the vinyl without smearing. 

Here's a prototype of what I'm working on, for context:



As an added bonus, I've found out that the material grabs my finger prints very easily, so preferably the solution will hold up to being wiped down periodically to remove prints.
I would try with a sharpie or other alcohol based marker. Look for the industrial version. 

As I wasn’t aware you needed colors, I didn’t recommend posca paint markers, which are acrylic-based and permanent. 

What it sounds like you’re going to need to do is to clean the surface to be painted with rubbing alcohol. The apply a fine mist of plastic primer from a spray can in several light coats. You can usually find them in most automotive shops. Then apply your marker and let dry. Cover with a gloss coat of spray varnish.

One last alternative might be colored nail polish.