Creating a ruby on rails site that uses RMagick to create thumbnails for many types of images. RMagick cannot read dwg files however.
I've tried a few things, looked into the Java library JDWGLib, which would probably allow me to write a converter, but it would be a total from the ground up solution, where I just need a thumbnail.
Also considered using a viewer program to open the file in a remote X session and do a screen capture, however I'm not sure how I could ever guarantee that the viewer had completed opening when I took the screenshot.
I'm not concerned with being able to manipulate the file other than to create the thumbnail. It is going to be used for commercial purposes, so any libraries used need to be compatible.