I am with Rose.. didn't think of this one and glad you asked.. I found a DIY website as well and wanted to see pics of creations and included a few and also some fun other license plate uses (love the individual letters). I like the rolled edge best as don't want anything falling off the side. I would be careful of these around kids as the thin metal edges might still feel sharp if fell on or grabbed quickly.
and one by KAT here on Hometalk