A recipe I discovered the other day:
1 Kiwi Shoe Polish Dealy
Oil Based Printmaking Ink
Paint Thinner.
Very simple, I based it off of the krink recipe, except that this is ink instead of paint.
The thing about the printmaking ink is that it's difficult to get into the container, and is extremely messy. I only put about say....2 bottle cap lids full of ink into the container, and about the same paint thinner, and it worked out nicely, very drippy.
You could use less paint thinner, but without it, the ink stays kind of solid, I had to shake it up to get it nice and liquidy.
Example of print making ink.