I was in Michael's Craft Store a few weeks ago and they had a big display in the papercraft area that stated "Rainbows and Unicorns are the Latest Fun Fab in Papercrafts". From what I've seen online and in many markets, they might be on to something.
In light of that statement and motivated by the word "fun", I have been looking at my stamps through rainbow colored glasses lately and what I might have stamped in black or darker ink awhile ago, I chose this silhouette #S613 "Birds on a Fence" to turn it into a rainbow image. The sentiment is #DF647 "Life is a Song". I thought the two worked well together, especially with this technique.
Instead of applying the inks with the ink pads direct to the stamp, I used my finger daubers, loaded it with the ink color then applied it to the stamp to the portion of the stamp where I wanted the color, then I stamped it. Without cleaning the stamp, I applied my next color (with a different finger dauber dedicated to the particular color family I'm using), some of the color from the previous color incorporated itself and I got a lovely blend from them. I did this with each color up the rainbow spectrum.
I hope this makes sense. It's really easy to do and it's such fun to watch the results take place.
What I think is fantastic about this technique is it can be used with line stamps or solid ones. So have some fun....let those rainbows flow and have some stamping fun.