Whenever I have left over ink on my craft mat after doing a technique, I mop it up with a paper towel, dry it and keep it for later. I keep using the same towel (one for each colour family) until it's saturated with colour and no longer able to absorb any more ink.
I used one of those towels to make this background. Placed it over a piece of hot press watercolour paper, spritzed with water, and pressed with my fingers to transfer the ink. The paper towel is quilted, so you can see that in the design.
Simply die-cut the lake loon for a card front, stamped a simple sentiment and popped it over the background. Super easy card.