Does anybody have any stories about time capsule projects?

Last night, my dad showed us this little hole thing in our house. I didn’t know about it – exciting! I thought I knew this house inside out, living here my whole life! Anyways, my sister and I got this idea – put a time capsule in there and open it in 2020 or 2025! We’re going to all (my parents, my brother, me and my little sister) write a letter to our future selves and collaborate on a letter to the “next generation” and then some stuff from our house before we remodeled, and some pictures of the “modern” technology. This is going to be so epic! By the time we open it, we kids will all be married and probably have kids. This will give my sister and my husbands and children a look into our childhood, and it will be great reminiscing for us kids! I’m quite excited about it. Has anybody done this and have stories that you would care to share? What did you put in?