I've been working on this guy for the past few weeks. In the current TMNT cartoon there were these 3 mutant Shredder clones, and only 2 of them got action figures, while the biggest and coolest one didn't. Shiva Shredder is the massive 4 armed monster that is half crab, half Ninja. Fortunately we happen to have a nice beefy 4 armed action figure available at retail right now in Machamp. The shredder armor is made out of apoxie sculpt, though I did use a finding Dory turtle shell to make his shell (modded to look more like a crab shell of course.)

On a bonus note this Machamp had a factory defect in that it had 3 left hands, I had to mod one of them into a right hand.