Berry,
You probably have already moved on with this and solved your problem, but just in case you have not, I have a suggestion that I think will work, I have some very this bambo that is extrememly strong. You could glue it on the back of your project wood and then your numbers with not break. The bambo is about the thickness of a piece of paper. I cut an ornament out of it that was extremely delcate, just to see how the bambo would hold up. I was able to cut it without any breakage. If you are interested in trying it, let me know. I can mail you some if you would like
Dick
heppnerguy