I used 8 colors of Atelier Ink on my rainbow background - all except Shark Tooth White, Twiggy Brown, and Paint it Black. I stamped a geometric background, but you could certainly use a ruler and a marker and draw your own background. I stamped first with Juicy Clear Embossing Ink and then with Blackout Hybrid Detail Ink and heat embossed with Crystal Clear Ultra Fine Embossing Powder.
I smooshed my Atelier Ink Pads onto my work surface and used a wet brush to add color to each area of my background. I tried my best not to put the same color next to each other and to evenly space out each color. Once my background was painted and dry I took clean water and flicked it onto my background and picked it up with an Ink Off Cloth. I repeated this three times to intensify the lift effect.
I didn't want to cover up a lot of my pretty background, so I added a few die cut sentiments and covered the large "hello" with Liquid Pixie Dust so that it would stand out. And that's it! I hope you give this technique a try!