Elbow Joints
Like most kits from this era, the elbow articulation leaves a lot to be desired. This is the result of problems with the original design (most designers didn't bother to actually plan for workable joints), and lack of good engineering on Bandai's part. Since the Gaz-R/L rely on some interesting melee weapons, I wanted a lot more articulation in the arms than is possible with the original parts. I spent a lot of time drawing different possible elbow joint configurations, and after several failed attempts came up with a joint system that sticks to the look of the design and allows a good range of motion.

The first problem is that unlike more modern designs, neither the upper or lower arm design allows much of a cutaway to make room for the elbow block to move. The solution was to build an elbow block that can extend out of the upper arm to allow the elbow to bend, and retract when the arm is in a more relaxed position.

Using a routing bit in my dremel, I first ground away the plastic inside the upper arm that holds the original elbow block to make room for a retractable part. I needed a new double jointed elbow block, which I started by building a simple rectangular box out of sheet plastic (some trial and error was necessary to get the length right). I drilled holes near the corners of the box on both ends to accommodate plastic rods (cut from the kit sprue), and installed t-joints which were cut down so they'd fit. Then I cut slots in the side of the box to allow the t-joints to rotate about 80 degrees.

Inside of the upper arm I installed a polycap to connect the new elbow block. It's held place in by a 3 sided box (u shaped). Since the elbow block is just plugged into this polycap, it can be pulled most of the way out of the upper arm, which gives it clearance to rotate (the polycap in the upper arm rotates a bit when this happens as well). The other end of the elbow block connects to a polycap in the forearms (allowing the same extension/rotation), which is held in place with short sections of plastic tube glued inside the arm halves.

Diagram of finished elbow block

Finished arm assembly with resin casting of forearm shield

The elbow was now able to bend well over 90 degrees, woohoo! Unfortunately, the power connectors (or whatever they are) that run from the shoulder to about half way down the bicep don't allow for a rotation point in the upper arm. So I had to add a rotation point at the center of my scratchbuilt elbow block.

I used a miter box to squarely saw the elbow block in half, and installed a simple polycap/rod rotation point. The parts are so small that I didn't have much space to work with, and the rod that plugs into the polycap is very short. I didn't want this to be popping out all of the time! From sheet styrene I cut end pieces to cap the sawed off ends of the elbow, and installed the rod and polycap before gluing them in place. I heated up a knife blade and melted the end of the rod flat. The mushroomed end of the rod keeps it from unplugging from the polycap. Then I glued the two elbow block halves together with the new rotation joint in the center, and sanded the whole assembly square and smooth. The assembly is a bit complex (and I still have to build 3 more!), but 7 points of articulation make for a nice poseable elbow. :)

After playing with it a little bit, I decided that I didn't like the squared off exposed edges of the elbow block when the arm is bent. So I filled the ends of the block with epoxy putty and sanded them to a rounded shape.

Details
The arms don't need much in the way of added detailing. I did cut away the molded in vent next to the wrist and replace it with pre-scribed sheet plastic (I hate trying to fix seams in the middle of parts like that!). There is also a vent of sorts by the elbow on the forearm, which wasn't very well molded on the kit (and had a big seam down the middle). I chopped this off with a hobby knife, and built a replacement out of sheet plastic. Basically it's a rectangle cut out of pre-scribed sheet, with a frame built up around it using plastic strips, then the frame was sanded to a beveled shape. It's small enough that it was quite a bit of work to make, so I took a mold and cast enough for the elbows on both kits.

The kit hands basically suck, so I planned to scratchbuild replacement hands which would be attached with ball-joints To simplify installation of the hands, I filled the end of one of the arms with epoxy putty to make a plug that fits snugly inside the forearm halves. Then I can just drill a hole to plug the ball joint peg into when I'm ready to attach the hands (I cast copies of this plug too).