we had originally planned to "unite" two pieces of a metal cross. I contacted a guy in Alaska who was going to make it for me. Unfortunately, he took forever to do it, and once it was done he wanted a fortune so we had to ditch the idea.
We did try to do a unity candle with hurricanes. But by the time we got down the aisle, the candles were already out. And then we ended up forgetting them. Oops. Oh well, didn't matter that much.
We also used the blessing of the hands.