Lots of apoxy, dremeling, and paint. We took a GI joe Cobra mountain playset, dremeled off anything that threw off the scale. We cut and fit a Hulk light up mask to the mountain, apoxied like mad, added teeth, and then resulpted the mask. We put in a railroad track and made the funhouse car from a a piece of the Fantastic car. Added a spike wall, and bunch of accessories. Even a Getia Scepter crystal which fits in with our expanded D&D Animated saga (mosetly in my head right now but we are working on a comic we hope to self publish when we're done).
Excellent, excellent stuff.