Highly custom Ender 3 running MKS 1.6 board and dual in/single out extruder : r/ender3
Dual Drive Gear Extruder Upgrade + E Steps on Creality Ender 3 - YouTube
Ender 3 dual extruder - second extruder mounted - YouTube
WINSINN Dual Gear Extruder, Works with Creality Ender 3 CR10 CR-10 Pro CR-10S Tornado Upgraded Aluminum Drive Feed for 3D Printer 1.75mm Filament : Amazon.ca: Industrial & Scientific
OMG V2-S All Metal Aluminum Direct Extruder Active Dual Drive Bowden For Ender 3 Update Orbiter Titan Aero E3D MK8 H2 V6 3D Printer | Vaughan 3D Printing
My custom dual extruder Ender 3 (It's named The Ender of Free Time) : r/ ender3
Voxelab Aquila Dual Extrusion (should also work on Ender 3 V2) by LilMikey | Download free STL model | Printables.com
Add dual extrusion to your current 3D printer - dual switching extruder guide - YouTube
Creality Ender 3 Pro Dual Extrusion Mod | Hackaday.io