Homebrew action figure designer Donald "KodyKoala" Kennedy is working on a theme here - guts. As in Guts-Dozer, of Mega Man 2. And as in King Hippo's dunlop spare tire.
On his Flickr stream, KodyKoala describes his Guts-Dozer as kit-bashed from the parts of a "Mech Hulk Top" and a "GI Joe vehicle that I used to have as a kid." I think that's the "Wolverine," the missile launcher that Cover Girl used to drive. Once again, I can't remember the formula for circumference of a circle, but I can recall that. And that's probably why I write about video games now.
As for HRH Hippo, I thought that 200-pounds-of-suet physique looked familiar. "I used a BLOB build [from the X-Men continuity] figure as the base, and unfortunately I had to make the legs not movable to make it look right."
Custom Guts-Dozer figure by Donald "KodyKoala" Kennedy [TinyCartridge via Go Nintendo]