What they are doing in next picture

I had forgotten to describe what the Bride and Groom were doing in the picture below, if you look closely you will see that each is pouring different color sand into one container...and the pouring of the sand mixes into a design..meantime the Minister is saying such words as the "joining" making one cloth out of two etc. I can't remember it all, I was just trying to take it all in...it was a lovely saying anyway. You get the idea.