Everyone knows about Krink markers, but have you heard of Illadel? Illadel ink mops are handmade in Philadelphia and are filled with opaque ink. Just like the Oink ink, it is difficult to buff and is fade resistant.
If you squeeze the bottle, the paint drips, if you don't squeeze the bottle the paint comes out smooth without drips. Because of the heavy duty nib, it works on most surfaces.
Thanks to James from Oink Art for the video using the Illadel Ink Mop.