Hi Marc, the tricky part about the .3DM built in thumbnails is not so much about generating them in the file, it's that the operating system does not natively know how to access the thumbnail to display it, I also have to write some additional plug-ins for the operating system that can give it the image from a filename. This has to be done separately for both Windows and Mac and it will take some studying to figure out how that's done for each platform and figure out how it's supposed to be installed. It's this extra chunk of work that adds up to some more time involved.

The file size does also go up, not by much something like 100 or 200k but it does mean that something with a few curves in it will not be just an 8k file anymore.

- Michael