We had great success with a family time capsule. We put it together in 1999 and opened it in 2009. The timing was such that the children were 7-10 years old when we assembled it. So they were in their late teens when we opened it. Any younger, and they would not have had anything to say, any older and they would not have changed much in the intervening years.
We had everyone fill out a list of favorites and predictions and draw a picture of themselves. We also had everyone include a secret message to their future self. The Favorites sheet is here: time_capsule_favorites.pdf.
A tour around the house, with pictures of the cars, the kitchen, furniture.
Video around dinner or TV
Video of everyone including and interview: talking about their life, what they liked and disliked, a tour of their bedroom and favorite toys and such.
Interviews with relatives
Ordinary, everyday things
Video of the kids’ activities (soccer games, gymnastics)
A complete newspaper, chosen arbitrarily.
Money and stamps
A favorite magazine
The calendar with everyone’s events on it
The video was very important. It was the highlight of the time capsule opening. It was very hard to make. It was difficult getting all the interviews done.
We didn’t bury it; we stored it with the Christmas decorations in a large tin can, which we duct-taped shut.