This is by the same artist as the Neon Zebra, and as I understand, they are both t-shirt designs. This is a different style, but it still has the play with negative and positive space, as the positive space is created by the colorful outlines and in a lot of places it blends into the background. This is such a fun, whimsical piece, and definitely allows your imagination to wander and create a story for the scene. I love the lazy days take it has too, yet the world appears to be flying, just like a dream. The color scheme is great too, there’s something very relaxing about it.
As far as creating this same look, I can guess that it just took a lot of patience with photoshop or illustrator (or both). Parts of it were probably drawn as a vector in illustrator, then masked out and colored and edited in photoshop. Overall, it’s a really pretty piece.