How can I preserve my older, or more delicate, RPG books? My collection includes some older books (from the 1970s-1980s), some of which are in less than stellar condition. They may be paperbacks, have loose bindings, etc.

I would like to preserve them for future enjoyment, but also keep them accessible. My contractor is salivating at the thought of building an expensive, climate-controlled room with each book individually held in a display case. However, that would make the books inaccessible and difficult to enjoy.1

I don't need a way to safeguard the entire collection, just a curated subset of the most valuable or at-risk items.

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1 My partner insists there are other reasons not to construct this room. Those concerns are outside the scope of this question.