This card was made using Smacking Acetate technique.
I haven't used this technique in a very long time, but it does make a nice background and perfect for a mailable Monday non layered card.
First cut a piece of acetate larger than the area you wish to cover.
Use stampin'write markers and scribble on the acetate. I used Island Indigo, and Soft Suede for the above card.
Next take a very fine mist water bottle and mist the marker covered piece very lightly. You don't want the acetate to be soaking wet because the colors will all run together and get muddy.
Here you can see how the water is causing the markers to bleed.
Next turn the acetate misted side down an smack it on the cardstock.
You can use your hand to run over the entire piece to transfer the ink to the cardstock.
Here is what the piece looked like when I lifted the acetate.
At this point way till the cardstock is dry then you can stamp over it.
I used Jet Black Stazon to add the images from Wetlands.
The fun thing about this technique is all the cards you make will have a different look as no two pieces are the same.