I did this.....added their picture and made it (you are an essential piece of the puzzle) I bought a puzzle of the game operation at the Toys R us store, spray painted the puzzle white and added color paper behind the pictures to create a colorful puzzle of the volunteers.

I did a party where I arrested my volunteers for freely giving away their time and talents. when they arrived they were greeted by people that were dressed in correctional outfits. They were escorted into a room where they had their mug shots taken and then sat at a table. The center pieces were canndles with ivy and barbed wire....prizes were awared.....a new washer and dryer (towel and wash cloth) candlelight dinner fot 2(2 tealight candles, canned food) lifetim manicure ( manicure set form the dollar store) home gym(jump rope) and more. Just go to the dollar store and use your imagination.
Have the other volunteers write reasons that someone else should be arrested for giving freely of their time and read them aloud. Takes the pressure off you to remember it all.