Here is a neat technique for a background using acrylic paints. First plop down a few blobs of paint in 2-3 different colors onto your card. Brayer over the colors once or twice. Let this dry. Then cover your brayer with bubble wrap. I used glue dots to keep it on the brayer. Pour some white paint onto a paper plate and gently roll the bubble wrapped brayer over the white paint and gently roll the brayer over one side of your first color brayered card.
On the other acrylic cards that I did below, I used felt nibs from Ranger, on my paint bottles and tapped the paint onto my stamps and stamped on my card. You will need to wash the nibs and your stamps real good when you finish. This has been a lot of fun and I hope you will try these techniques. Makes a new and neat look to your cards.