This design also started as a contest submission, but I won't put unnecessary limits on it. It's now available and updated with new art.
The image was drawn in Photoshop using a Wacom Tablet and pretty standard brushes. I used a hard round brush with shape dynamics for the main illustration in all the colors, and in the rest a series of texture brushes with flow and opacity using the pen pressure, lots of layer masks and the eraser. Initially this image was designed with a number of layers, each color on it's own layer. Then I got back to basics, flattened it and finished it with a light blue sketchy background. I'm still sure it'd print better if I could just send them the seps I did, but Redbubble doesn't seem to allow submission of layered files so that's out anyway. Hence, flattened.
This style of design is a lot closer to something you might see in my acrylics or watercolors - in terms of form, flow and shape, though it's still really an illustration more than a painting for all the hard edges and flat color. The light blue background is vaguely in the shape of a two headed arrow. The arrow points in opposing directions without a center, at each end sit a particle of matter and it's anti-matter particle. Particles that were once single that were torn in half and will probably never meet again. Can they still feel each other through time and space? Do they long for their "other half?"
One may never know.