As well as making prints in the studio with the big presses, I also make them at home using nothing more than an old chopping board, watercolour paper and a roller or a wooden spoon. I started by taking impressions from my palette after a painting session, rather than throwing away the unused paint.
I smoosh (technical term!) the left over paint around on the palette - I use an old plastic chopping board with a smooth surface - and then take an impression onto half sheets of watercolour paper using a roller or the back of a wooden spoon. Sometimes I can get a second impression by misting either the palette or the paper with water first.
Once the paper has dried, I take some old mounts with various size apertures and move them around the sheet looking for patterns and shapes that catch my eye. I often see little imaginary landscapes for example. When I find a likely candidate, I cut it out and mount it up. Even with a digital print, there is something about mounting them that turns them from a piece of paper into a special object, and that transformation is even more acute with these scraps of paper, that may not even be rectangular.I have some of these in Etsy my shop at the moment.
You can see some others used as the background for ATCs here:
http://www.ipernity.com/doc/panchromatica/5702037
http://www.ipernity.com/doc/panchromatica/5702031I also use them as 'prepared papers' for collage:
http://www.flickr.com/photos/ibanda/3330055541
http://www.flickr.com/photos/ibanda/3651227771
There is a monotype behind this one too:
