An idea from the Liverpool (North) Circuit who used the theme of Our Rock of Prayer.
People who signed up to a prayer rota and people attending services were given a palm sized pebble to hold as they prayed. The theme offers the potential for individual interpretation but all the pebbles (and prayers) were gathered together to form a cairn.
Cairns are traditionally built as memorials or waymarkers. Maghull Methodist Church have a prayer cairn outside their building as a permanent reminder of what prayer can achieve.