My father is a puzzle enthusiast. We have (multiple times already) taken a family picture, printed a puzzle from it, presented it at a birthday party, had all the guests (up to > 50) sign in colorful markers on the picture, then disassembled it and gave him his puzzle to "work on". After finishing the puzzle he glues them on some support and hangs them as a picture, a memory to both events, the one on the picture and his birthday party. Sometimes when his friends come to visit him they search for their own signature, asking "was I at that party?".