I got my armor as well from the Jodo meister. I plan on completely cutting my slots out and using an extra, larger piece of sintra, and gluing it to the back side, covering up the slots. This will eliminate having to carve, chisel, plane, or otherwise weaken the already thin material to get the look I'm after, which is two smooth indented rectangles. I plan on using this same technique for the center diamond piece. I just need to get extra sintra, lol.
In the meantime, I am enjoying dremmeling my dwedd helmet one square millimeter at a time. Dremmels rock! I have the nose area done. Working on the eye areas now. Am taking pics of my progress, though I don't know if my "close-ups" are close enough to catch the detail. I'll continue to post on my "wish me luck" thread as I go.