I agree that 3 3/4ths is far too small to properly make new Centurion's toys. That scale works best when you have figures that need to interact with vehicles and playsets like Joes or Star Wars figures do. With Centurions, who in and of themselves are more or less vehicles, 6" figures would probably be the best way to go. They're small enough to make them and their accessories affordable while big enough to work in a lot of attachment ports and articulation. Short of some sort of interlocking magnetic system (which would probably make the figures more expensive) the good old peg-and-hole concept is the most reliable way to go.