We've seen some interesting approaches to tattoos lately. Stick-and-poke continues to be on the rise, and black-out designs are on the up-and-up. Now, another ink concept is (quite literally) popping up: 3-D tattoos.Portland artist Dave (who goes by the name Winston the Whale ) is catching the attention of Instagram users with his trippy, red-and-blue creations. But they're not quite like the eerily realistic illusions we've seen before (if you google "3-D tattoos," you'll see what we mean); they're a bit more playful.Dave told The Huffington Post that he started out doing stick-and-poke tattoos, and that the 3-D concept began at the request of a client. “I suggested a simple skull," he said. "He asked me if it was possible to do it in red and blue like a 3-D image, and I figured it was worth a shot to at least try it.” The image blew up on Instagram, and he decided to continue the concept."It’s really about delivering something that is stripped down to the basics for maximum impact," he told The Huffington Post. “People only really look at an image for a second or two, and these little 3-D designs capture their attention for just the right amount of time.”Click through to check out some of Dave's work in action — no 3-D glasses required. In fact, Dave said they don't work when it comes to viewing 3-D images on the skin, to the disappointment of many (read: this beauty editor). "Unfortunately, there are several factors to making an anaglyph image effective and the contour of the body, skin tone, color overlap, etc....negate the actual anaglyph 3-D effect,” he explained. Sigh.Either way, we're intrigued — and would love to see these in a non-permanent form as well. ( Flash Tattoos team: Are you taking notes?)