Here’s what I did:

1. Mist plank of wood with water

2. Create desired design/pattern/lines on the board with 3-5 colors (I was following the woodgrain roughly)

3. Cover carefully with plastic wrap

4. Mist with water and run fingers along the top to manipulate or blend colors together

5. Remove plastic wrap in one direction

6. Mist lightly with more water

7. Looks best sealed with epoxy or similar high gloss coating/sealer

😄😄😄