Prior to worship on a Sunday morning, outline a cross in masking tape on the floor of a carpeted room.  Apply scotch guarding and water proof in that area.  On Sunday morning, ask people to confess what has stolen their attention from their true identity, distracted them from what the kingdom of God is about.  Have people write this in the area that was waterproofed on the floor (removing the masking tape so they can’t “see” the cross ahead of time but having volunteers direct people to the general grid).  Sins should be written in washable markers.  Pronounce an absolution and have volunteers throw lots of water on the floor.  Watch the marker disappear and the cross appear.  For an extra added bonus – have people walk through the water on their way up to celebrate the Lord’s Supper as a reminder of their baptism!

Great if your carpet is about to be replaced or if you have someone with a wet/dry vac who can suck up the remaining water afterwards.

To see an example:   https://youtu.be/BZ5zIeEEbY0