I got my solder pen for $5 at Walmart. It's got a pen-like tip so it's very easy to use. (just wanted to add to that question).
Yes, as many photos as you can add while describing the process will be most helpful for others. Considering the modification, I think that's still totally feasible. Thanks so very much for your willingness to work on this and share it with our community; it's very much appreciated!
Looks like I may have some cosmetic surgery to do after my second Kup comes in. I think I have figured out a "non" partsformer cheat to that mod. After I get it to work I will share some pics.
Since I will not get to implement my take on this mod for a few weeks. I will share it now. Basically the gist of it is Zaku hoses: HG Zaku II Rebuild - a set on Flickr You make some Zaku hoses out of craft beads strung with some tough fishing line or cord. You then install them inside the rear fender area near the knee and then run it to the side panel so there is a "technical connection" between the side panel and the leg. I figure if it can work for Ultimate Bumblebee's doors it can work for Kups arm sheilds. It would work something like this: () Round Bead [] Cyllinder Bead Leg/Fender|()[]()[]()[]()[]()[]()[]()|Side panel/sheild. (Pro-tip: leave about half a beads worth of slack so the Zaku hoses will flex easily.) The parts would would just swing back behind the leg and peg in like the original mod shows. While still technically plug-N-play, at least the panels won't get lost this way.
It took me FOREVER to find a store that actually HAD a Kup. Even just sitting out on display now the bulkiness of the arms bothered me. Simple mod that makes a world of difference, props on the idea!
I tried this and followed the directions to the letter. In the end the door panel ripped off it's peg instead of popping off the rivet/pin. This happened after several attempts with the soldering iron. Was the pin simply not hot enough?
removing the door panel from a hot pin should be effortless, my guess is the pin my not have gotten hot enough, make sure you give the sildering iron plenty of time to heat up before counting (if you turn it on and imediatly try to heat the pin it will take much longer than the recomended 40 seconds) but i have had instances where i pin did not want to come out and required more time. there is a tutorial on pin removal as well found here http://www.tfw2005.com/boards/tutorials-how-tos/214537-how-remove-pins-rivets.html
I like it, I think I will just plug up the hold though with some putty on the forearm. I'll leave the backside open though for the panel to go back in for alt mode. It looks a lot better than before though, that's for sure.