Okay, after a long delay ( in part, having to do with a virus apparentli sent by Photobucket ), I can finally post some progress pics.
I finally decided to use a less-complex plating pattern on the forearms than was in the original art, but keep the parallel lines on the upper arms. For the first arm I worked on, I marked four of the eight lines, scribed those with magic tape to keep them straight, then tried to scribe the lines in between by moving the tape to what seemed to be midway between the first ones. The resulting pattern came out less even than I'd hoped, and with the lines not deep enough for the effect I wanted. While working on other projects, I tried to think of a solution, and after a few weeks came up with an idea that took care of both issues pretty well. The added depth I wanted was a simple matter of using a file with triangular cross-section to make the lines deeper.
Instead of starting on the sides, I marked and filed at the corner.
This made the spacing a lot easier. From there I lined up the tools and started scribing. The magic tape was pretty easy to line up since I just had to use the nearest end of the gray arm section for reference.
I used all 3 scribing tools to gradually make the lines deeper. The pen-type one seemed to work well at avoiding some of the slipping and straying I've occasionally had with the other two, so I used that to set a guiding mark. From there, the one with the smaller hook actually scraped out plastic for the line ( the pen-type did little more than scratch and push plastic out to the side, which makes for easier corrections but not a very effective guide ). The one with the larger hooks on both ends could then be used without the magic tape to deepen the lines further and continue scooping out plastic.
After these scribing passes, here's what I had.
Now that the lines were in place, I deepened them further with the file.
Using the grooves on the edge as a guide, I then filed the prpoer places at the second corner, used those to guide the next set of scribed lines, and complete the process. After doing 3 sides this way, the last used the filed parkings on the corners instead of eyeball lineup with the top and bottom edges to line up the magic tape. Here are the arms for comparison, with the "new approach" on the right.
The next bit of customizing I had in mind had to do with the lower face of the center torso. While I wasn't up to the interior buildup that the opening in the original artwork would require, I didn't like the plain panel on the kit, either.
I decided on a covered vent as a compromise, using the existing panel lines as a start. First, I scribed the lines to place the vent slots.
From there, I very carefully used the X-acto to chisel upwards toward the scribed lines, creating the slanted vent effect. I may to a secon pass to add more depth, but here's the general effect.
More sub-assemly work to come, and I'm also trying to figure out how much detail I'll be adding to the cockpit. More pics on the way as I make any notable progress.