Don't worry: there isn't really a frog chilling on a piece of paper on a desk. Serbian artist Nikola Čuljić, 30, draws incredible flat works of art that expertly appear to be 3D. Čuljić recently shared some of his art on Bored Panda, where he revealed that he is a self-taught artist who has only been actively drawing for under three years. "I started drawing portraits and it was hard...so I decided to draw something different," he told Bored Panda. And he drew something different by experiementing with perspective and became an expert at turning a two-dimensional piece of paper into a 3D optical illusion. While Čuljić has made a career out of being an artist, his 3D drawings are not for sale. He told Mashable that his goal is to make his, "name a brand for 3D," so perhaps his pieces will be available for purchase in the future. Art fans have been reacting positively to Čuljić's work on Facebook and Instagram, and he told Mashablethat he has really enjoyed the "wow" reactions he's been getting. All Čuljić uses to create his paper masterpieces are colored pencils (which are his favorite, he told Mashable), markers and pastels. A magician never reveals how he does his tricks, but artists aren't magicians. So, Čuljić was happy to share his process with fans in a video.