Wow, I had no idea someone has thought of this too. I thought of this independently, but it's obvious that the mechanism would be the same. I'll probably print this for myself and a friend, but I don't want to upset the original designer by selling it. At least one difference is that the one I designed is closer to being cubic . I should make it a perfect cube and call it "Cubic Master Quartet"
Make the core a 2x2x2. That would add minimal changes yet make it a brand new puzzle. Don't waste your money prototyping an old puzzle unless you really like the design.