Sync is a great mod, and it was in steve's galaxy. It adds 3 items, the Shell Creator, Shell Storage, and Sync Core. It allows the creation of "shells" which are clones. But these clones don't have minds! That's where you come in. Supply a Shell Storage with a redstone signal and then walk into it after creating a Shell in the Shell Creator, and select the shell! You can then walk around as that and even see your old shell. You can switch between dimensions and over long distances. It's an overall good mod.