Instructions
Enter Forge mode and hit the "X" button to edit Forge options. Under "Shields and Health" choose "Damage Resistance" and lower it to 10 percent. Exit out of the menu and start Forge.
Press up on the directional pad to enter Forge edit mode. Pick up a crate on the map and select the crate under "Objects" in edit mode. Spawn one crate and a spawn a machine gun turret next to it while in edit mode.
Move next to the crate and press the "A" button to pick up the crate. Look up with the analog stick until the crate is directly above you. Press up on the directional pad to return to player mode, and let the crate fall on top of you.
Get behind the machine gun turret and hold "RB" to grab the turret. Press the "B" button and you will successfully create a clone.