Our friends at E3D have taken the gearbox from the Roto and packaged it in a lightweight mechanism that is easily adapted into different tool heads. The Roto Vitamins combines a planetary primary drive with a spur secondary and dual hobb third stage to offer incredible extrusion force. There are files available for Dragonburner and Stealthburner toolheads- go to this link and check the “Upgrades” tab.
You’ll also need to purchase a motor, you can get it here.