You considered sculpture? Since you do custom vinyls, you have experience painting three-dimensional forms. It's a straight shot from there. I'd recommend this gunk called "Cellu-Clay" which is basically paper mache that you can manipulate like clay. It has a crazy texture when it's dried, and you can make all kinds of awesomely horrible abominations with it. Link me to your Etsy when it's ready, I'm sure I'll find something I like.
Speaking of awesomely horrible abominations, here's a few more of mine.
This one I actually drew in about two minutes at the behest of Matt (Dipstikk) who wanted me to throw out some concepts for a storm elemental. I sent him the design via phone using the phone's camera. Now it's scanned.
A seriously fucked-up rendition of Goofy. There's one or two pages of my sketchbook filled to the edges with just twisted versions of classic cartoon characters. I'll scan them and put them up when I get around to it.