I really like the atmosphere and look of Apocrypha, but there's really no need to revisit after doing the respective plane. I also like to collect books but I've never found a library mod that I like, so if I had the ability to make something with the Creation Kit, it would definitely be a library using Apocrypha assets, accessible by reading a Black Book. There are many cool effects in Apocrypha IMO - whirling sheets of paper etc.

The problem is that I really hate working with the Creation Kit (a frustration which only makes it more amazing to me that so many awesome mods are made with it). Anyway, if someone thinks it's a good idea and have the ability and time (yeah, right...), it would be like a christmas gift that keeps on giving (or how that expression goes).

I'm not looking for a HUGE library - in fact the cozier the better. It would be cool with self-sorting shelves. Also, to top it off, displays for other unique items (dragon claws, dragon priest masks etc.) would be really nice.

The creation kit is very easy. There are tutorials online. There's a whole wiki dedicated to it. In the time you spent making this post, you probably could've made a basic library. You'll regret not learning how to use the creation kit much more than not having a cool library. Self-sorting shelves is a bit more than basic editing, though.

I've messed with the Construction Sets lots of times, but I just hate working with them - and the thing I dislike most is navigating in the render window. It would probably give me a coronary before I finished my first simple room. I much rather mess with TES5Edit, which is logical and stable - but not made for making libraries of course. One can download the sorting part so that's probably not that hard to add.