I've been pondering this and came across a great, fun tool at:

http://www.pictureframes.com/scripts...a/wa/FrameShop


(join up the line, if it gets split!)

You can try out mount sizes, colours and frames. You can even upload your own image, and find a combination that works.

I'll probably cut my own, rather than ordering from them (as I suspect I'll want quite a few), and I'll do some real tests first, but it's given me some good ideas as a starting point.

Ian