In theory yes you could do it. But it is not going to be fun getting 7 characters from 1 to 70 alone, or getting them in a place where they could farm high torments for these items to drop fast, only to spend all your time doing dungeons, and some of them are really frustrating and rng dependent at some extent. But yeah if someone held a gun to your head and said do it, you would probably do it in a couple of days, lol.