I have thought about such donations myself. I would be
good to get
document signed to the effect that if no longer wanted, the property must
be handed back to the doner or doners heirs.
I doubt that any "real" museum would be willing to accept any donation
under such conditions. Generally they'll only accept donations with no
strings attached.
Even with objects provided on "indefinite loan" rather than donated, they
usually won't accept conditions.
I imagine that if a museum wanted something badly enough, that things might
be different, but it would have to be something *far* more rare than e.g. a
PDP-8.