The technique uses glossy card stock, re-inkers and a water spay bottle.
On one of the pieces of glossy card stock, drop on some of the lightest re-inker color, then drop on less of the medium color re-inker, and then just a few drops of the darkest re-inker color. Spray a few times with water.
Lay the other piece of glossy card stock on top of the wet ink and press together, twist a bit as desired. Then carefully lift off the top sheet.
Here's how it looks, the colors seem really intense because the ink is still wet.
I tried to speed up the drying process by using a heat tool, I like how the heat tool moved the ink around into this pattern.
Decided to try again, using less re-inker drops.
Here's how it turned out.
For fun, sprayed on a home made spray with yellow re-inker and gold Perfect Pearls.
One more try using blue and purple re-inkers. Used more water sprayed on than in the sample above.
The outcome is lighter than I wanted.
Added more blue and purple re-inkers in spray bottles and smooched and swirled. Like how this turned out: