Have been creating some more collage papers today.
The way I do it is to paint onto a styro-foam sheet with a mixture of watercolor and acrylic paint, then press the paper on top and rub gently all over the paper to transfer the paint. This is done several times to build up layers of texture. This stuff is really addictive!
For the print below, I built up several layers of paint first, then on the last print I drew into the paint with a cotton bud before transferring the image to my paper. It reminds me of fossils.