One of the Silhouette Yahoo group members asked me for a video on how to make a 3D graphic usable. One look at the graphic told me it would be pretty much impossible to trace directly in Silhouette Studio because it had primarily light areas on the edges. You can, of course, take a graphic into Photoshop and make a blackout of it and other things but I realize most people do not have the program and/or don't know how to do this.
Anyway the graphics are opened in Silhouette Studio and the first thing you need to do is to cut the multiple images apart using the knife tool. You can also trim off the excess "white" space at this time. Then you just have to start tracing around an object. I usually go in VERY close to do this and just start clicking and placing nodes. I am not really all that careful when I do it. One reason I'm not that careful is that I know I can't do a great job as my hand shakes sometimes and I know I'm going to have to go clear around it and adjust the nodes when I finish...so I might as well just click around quickly and then spend the time adjusting the nodes up to the edges of the graphic.
This is a case of "how badly do I want to use this graphic." If you want to use it then you have to spend the time to make it work. The detail the Silhouette is able to cut makes it oh so worthwhile...at least to me.
Below is the video showing how to get started on a project. Be sure to watch it on YouTube if you want to see it on a larger screen.