GN-R4 Gundam Oberon (update)

Here is a better look at how I did it. I simply drilled a hole into the back skirt, added pla plate to the backpack part, drilled a hole into it, glued a piece of runner in it so it can peg into the back skirt armor. 

I also did some pla plate work on the newly created GN Burst Cannons. I came up with settings for them as well:

GN Burst Cannons:  Powerful GN particle cannons connected to the rear of the Gundam Oberon. They have  been upgraded with a variable output function. The pilot can choose the type of parts beams the Cannons fire. They also now have a rapid fire mode. Not as powerful as it's standard firing mode, but they can still do damage to enemy units. They're connected via a movable track. This track also supplies the cannons with GN particles 

I was working last night on rebuilding the chest on the Gundam Antares. I'm having trouble cutting the pla plate out evenly so I ordered a hobby saw and it will be here Friday!! Hopefully that will help me with my scratch building skills