Rubber Stamps and what? I know- it sounds crazy, but I had some Drawing Gum (aka Masking Fluid) laying around and I had never really used it because my drawing skills/watercolor painting skills are still in their infancy. So I thought, as I always do, hmmmmm I wonder if that would work with Rubber Stamps? Turns out, it does! Have a look-see at this video to see the process. I apologize in advance- it cuts off a few times since I was dealing with limited space on the video camera.
Here is the end result: