Another thing you can do is put somthing really tall. ie. a radio tower. Then, put one on top of it. After chaging the respawn times of the fusion coil, delete the radio tower. When the coil spawns, it falls all the way down and blows up when it hits the ground.

you have to use fusion coils.
in forge pull one up and press x. change run time minimum and maximum to the highest number and make sure the respawn time is on the fastest time. then set them off with a grenade or something.