Thanks Woody. Sadly I traded the big Lyran away and will never see it again.
I've been using Bondo spot putty, which is cheap and behaves much the same as Squadron green. I also used Tamiya 2-part epoxy putty on the Ranger, for the curved bit at the warp engine "pylons". Thinking ahead toward a possible next project of maybe the Kzinti, I might try your concoction of styrene and MEK.