A will should be a living document. It should be reviewed, reconsidered, and revised formally about once every five years...ish. It must be made available to at least one other 'trusted agent', usually known as the executor, who will know what you mean, even if the will doesn't quite 'say that'. [Consider revising the will if what 'you mean' and what 'it actually says in words' cause some frowns.)
I will offer my toys to anyone who expresses a convincing interest in them. If they would like the chore of dismantling the layout and reassembling it in another shelter, by all means...saves me the hassle. If nobody expresses a particular interest in the layout, I hope to be in a position to dismantle it myself to dispose of it before I'm incapable. This will take an honest self-appraisal and good timing. If not, I'll pay for someone else to back out a few screws/take a sledge hammer to it/burn it while I'm still able to direct the activity and express satisfaction with the end-state. If it's still in place when I die, I'll have that covered as a contingency in the will. Hopefully.
Ideally, one of my grand-sons will want grandpa's trains...the rolling stock and maybe some choice structures and turnouts, etc, especially the handlaid ones in the latter case. Or, both of them will want a share. At the moment, our mutual bond is trains, whether watching videos or me letting them play with mine. Things change though. Not only puberty, but new discoveries, new passions, new success, new fame....in anything not related to trains. But, if not, see the first statement in my second paragraph above.
My overall philosophy on this topic is this: what I don't know don't hurt me. My aim is to avoid it becoming an emotional burden to my wife if she outlasts me.
