One thing that won't work is the "what exactly is the paint" thing. Even if the paint is still made, and the colour code is still valid... the paint won't match it. Paint fades over time. So you might as well just take a chip of it to the paint store for matching, and resign yourself to having to repaint one "surface" (to the nearest corners).
As for hidden "time capsules" - I actually left one of those as a kid in a house that was being built at the time. About 45 years later, with me long moved to another continent, that wall was being modified and they found the note behind the paneling and sent me a photo of it. I hadn't remembered leaving it there.
As for hidden "time capsules" - I actually left one of those as a kid in a house that was being built at the time. About 45 years later, with me long moved to another continent, that wall was being modified and they found the note behind the paneling and sent me a photo of it. I hadn't remembered leaving it there.