I cut the acetate into people shaped pieces and then we wrote or drew on them things I was sorry for or the names of people I'd hurt.
Then if you dip the people in a container of water, as a symbol of confessing your wrong to God and asking Him to forgive you, the writing dissolves and you are left with a clean person!
I tried this first using dry wipe whiteboard markers, but it took a real effort to scrub the writing off! The type of pens that really worked were washable felt tips. The writing came right off as soon as the surface of the person hit the water, but that type of pen doesn't show up too well in the photos unfortunately!
The children love this kind of visual when they are asking for forgiveness so I am looking forward to trying it!