There also is a device designed to teach the English language to the Crypt's finders. Jacob's idea in 1936 created tremendous interest. The Oglethorpe Atlanta Crypt of Civilization Time Capsule. A 50-year or less time capsule may be witnessed by your own generation. The longer the duration, the more difficult the task.
Committees are good to share the work load, but a single person needs to direct the project.
A safe is a good choice. As long as the interior is cool, dry and dark artifacts can be preserved. Many things your committee selects will have meaning into the future. Try to have a mix of items from the sublime to the trivial. Items are usually donated.