Be careful about your hermetic seals, water leakage has turned many time capsules into a soggy brown liquid. I suggest some silica gel (the kind you shouldn't eat) to absorb any latent water in the air when you seal it so you don't get condesation.
Anything you seal inside should either be readable by normal human means or include the reader. Avoid batteries or other volatile chemicals as they will leak. Burned CDs are really just like polaroid photographs and fade in about 15 years on the outset depending on the burn speed and qualities of the dyes. Include black and white photos or 3 color separations so that it is easy to put back together. Same goes for 3d photos, the future is likely to use more stereo photography so take a picture with 2 cameras next to each other of the same type. I use two iphones and tap the shutters simultanously a few times to see if I can get a match.
Make sure you deposit the item in a place unlikely to face future development or it will just be shoveled up onto a trash pile.
There's a start, but think long term. A lot can happen in a quarter century. LONGNOW DOT ORG