Sadly, the originals are only done to be printed at a maximum of 4"x6". I started them mainly as practice in SAI, and then they became ridiculously popular! I'd love to get them printed as postcards, and I was trying to make a poster with all the main figures in it, but I stalled out trying to figure out a background. ^_^;
I have *really* thought about re-doing them at a larger size... 11x17, or thereabouts. Right now I just have no time. x_x My video game project is starting to pick up, so I'm working like crazy on that, but maybe it's something I can work on slowly in my "free time" (haha). I'd like to be able to offer them on shirts on Redbubble, as well.