Our Stretch Cat design has been such a huge hit as a rainbow holographic sticker that I just restocked them in our shop! These are thicker than our other vinyl decals, and great for indoor or outdoor use. Put them on your water bottles, vacuum flasks, cars, phones, laptops, washing machines... whatever! They'll change color depending on how the light hits them.
I've been asked a few times about making custom stickers, and wanted to point you to Sticker Mule, who makes these stickers for us. They're a great company to work with, and they have a ton of products available. The even have some great new tools to help you turn your graphic into the stickers (or coasters, magnets, and more) as easily as possible. Try out Trace, Upscale, & Redraw with your own graphics to see what you can make!