Checking the registry on Windows (SUv2016) the “ThreeDText” key does not even exist if the user has not yet used the tool for that particular SketchUp install.
Now I just used the 3DTextTool, for the first time in this clean install of v2016, and then refreshed the Registry Editor view, and Viola! SketchUp immediately writes the settings under the new keys “ThreeDText” and “ThreeDTextDlg”.
… Now I just used it a second time (changing fontface, size, etc.,) and after placing, SketchUp immediately updates the registry attributes of these keys.
So, @gkernan Garry, you can use the registry read paradigm for Windows.
(Pay heed to the correction I added to post 5 above.)
I don’t know if it works similar on the Mac. Perhaps John can run a test.
I also wonder if Ruby PStore lib can read OSX plist files?