Mike(BD55),
When I did my first multi cut out piece, I made what I think might be a common mistake. Maybe it'll help you before you try. Make sure there is enough distance between the 2 items you are matting. If you are single matting the items, the distance only matters from an asthetic standpoint. If you are double matting, you need to remember that the top mat will be at least 1/4in smaller than the bottom mat. The problem I had was that my 2 items were too close and after subtracting 1/4in from each cutout, the top mat wound up very thin. It was not only difficult to cut, but also didn't look right.
Pictures will explain what I mean better.
Here are 2 pictures of Mel Ott that I matted. Notice the size of the brown top mat between the 2 images.
Now here is the Gehrig group that I put together. Notice how thin the top blue mat is between the Picture and the Sporting news book. I didn't leave myself enough space to get an even amount of Blue top mat in between each item. I have to tell you that this thing was a pain to do. I'll probably redo it at some point.
Good Luck,
Mark