The proton pack is radically different from what has come before it. Gone is the cyclotron and the independent power source, the pack is powered by canisters that are plugged into the back of the thrower. You can see one of the canisters hanging off the back of the pack in these production sketches.

JoeLuna’s fantastic EGB pack build, the build thread can be found here.

http://www.gbfans.com/community/viewtopic.php?f=2&t=2688