Storing items in a sealed chest for 25 years

accet87 writes: "We are celebrating the Silver Jubilee of our graduation next month and have come up with an idea where we will build an air-tight chest in which each of us will deposit something and will open the chest only on our Golden Jubilee, i,e, after another 25 years. I want to understand what kind of items can be safely stored for 25 years and what kind of precautions are required to be taken. I am sure things like paper, non ferrous metallic objects, wood etc will hold good.
What about data storage elecronically? I dont think CD/DVD etc will be usable. Even if the data is retained, reading it in 2037 may be a challenge."