I had heard of this technique on chat forums about making ATCs in the past. Now the technique is represented and explained in the book "Artist Trading Card Workshop" by Bernie Berlin. Since I knew it before and it is not a big long process I'll explain it here.
You basically put paint onto a baby wipe. Period.
Some people use baby wipes to clean up their ink or paints. Then they dry the used baby wipes out and use them as backgrounds.
For mine, I did some with watercolor paint (intentionally) and some with liquid acrylic paint (intentionally).
For some of a different but similar technique I used paper towels to clean up alcohol inks, another time: rubber stamp ink and another time: acrlyic paint. Then I used the dried out "rags" of paper towel to make backgrounds for the ATCs.
Each brand of paper towel and baby wipe has different patterns or embossing to them, so there are numerous possibilities. One baby wipe brand we had in the house was covered with tiny teddy bears. I didn't want that but maybe someone would like that.
You can either use the solid sheet as a flat background or you can tear the toweling or wipe randomly and layer it onto a stiff background material with acrylic gel medium as the adhesive. Let it dry then do whatever you want on top of that to make an ATC. This of course would also work for other things like larger collages.