I watch the blog hop at PTI every month - drooling over the gorgeous creations but I've never played along before. I only have 10 PTI sets so far (I find their overseas postage costs prohibitive but now thanks to a lovely friend who is Stateside I have the chance to get them shipped to her and forwarded on much more cheaply) so often found I couldn't shoehorn one of my sets into the theme. However, this month the theme is just to create a card on a black background and I knew I could make that work! http://nicholeheady.typepad.com/capture_the_moment/2013/01/january-2013-blog-hop.html
I heat embossed a sentiment from the Movers and Shakers Sentiment Set in white onto a black card base and then created a rainbow in the background using polychromos pencils which have strong enough pigment content to show up when applied directly to black card. I then die cut some clouds and popped them up with dimensional foam over the rainbow. I finished with a white dotted line around the outside with a white gel pen.
It's also No 69 on my list of the 75 card challenges - make your own rainbow. See the tab on top of my page for links to the other 74 cards on the list.....