Hi, any news in your journey to Duet?
There is an active facebook group about the installation of duet3d on a idex printer similar to yours here: https://www.facebook.com/groups/237163797566846
This is not the T-Rex, but the tenlog / hictop printer, as far it is worstthan formbot, is quite similar to your printer and this can hel pyou finding a starting point.