On forge mode, go to the level narrows.

When you get there, go to one of the grav lifts that shoot you from one side to the other.

once you get there, go to the drone dude and go to the list that says scenery on it.

Go to the very bottom of the list and get a grav lift.

Once you buy it, put it either in front of the giant grav lift, or put it somewhere straight in front of the giant grav lift.

Repeat the same exact thing on the other side.

Finally, once your done with that, put a fusion coil on top of the grav lift that you put in front of the giant grav lift.

After that fusion coil lands and blows up, do the same thing on the other side.

This glitch does best with two players. Repeat this cycle over and over again.

When you do this glitch, you don't just have to use fusion coils, my friend and I used weapons, teleporters, etc.