How would you like to actually be able to fill a shelf with books, or even other items? With the original script, you can only put up to 18 books on the largest shelves, which will only fill the shelf if the books are all the largest size. It's really annoying when you 'fill' a shelf with small books, and there are giant gaps between them.
So, I made my own bookshelf script, which places books based on their width rather than fixed positions. You can place as many books as will fit on the shelf. The result is identical if you use the largest books, 18 to a shelf, but you can put around 90 notes or bounty letters on a single shelf (if you ever get that many). You can now also place any other item on the shelf, not just books!
-The time it takes to update the items on the shelf is similar to the vanilla version, just a little slower. However, the more books you place, the longer it will take.
-You can always put up to 128 items in at a time, and when it goes to place them it will simply give back anything that didn't fit.

Know issues:
-If you load a save made before installing the mod that is inside a house, the bookshelves in that house will not work until you go outside and back in.

-Most enchanted apparel and some mod-added books/items register a width 0 and so will pile up (let me know which mods do this so I can contact the authors about fixing it). I may get some of the enchanted apparel fixed, but it's time consuming so don't count on it any time soon.
-There is no check for the size of items, so if you add items that are too big they will clip through the edges, and if they fall out entirely they will disappear the next time the shelf updates.
-The orientation for items is picked automatically. If something had an orientation that you don't like, let me know and I may be able to change it.
-Soul Gems and any other item with individual data (such as charge on enchanted weapons or stolen items) will lose that data. The item visible on the shelf will be a copy without the data (no soul filled, fully charged, not stolen), though the item in the container will still have it. So, for now just take soul gems out by opening the container, not grabbing the item on the shelf.

-If you have issues with a specific shelf not displaying books, getting stuck books that can't be removed, duplicating books, or whatever, try using the 'reset script' download. Instructions in the readme that comes with the file.


Installation:
Use the mod manager or just extract the files into your skyrim folder. It's just 2 script files that go into Skyrim\Data\Scripts\ and a .esp that goes in Skyrim\Data.

Compatibility:
This mod will be compatible with any mod that doesn't change the bookshelf container script. Mod added books are mostly compatible.
Some mod added books will get placed on top of/inside other books, let me know if you see this and I'll contact the creator of the other mod to fix it.
ALL bookshelves, including ones added by other mods, will be affected as long as they don't use their own, custom scripts.
-Dovahkiin hideout is compatible, except the unusual 'shelves' on the stool and the desk don't quite work as intended. Instead of the special placement, books on those just get placed in a straight line/stack.

-Books Books Books is now compatible (Note from Nazenn: Book Covers Lost Library should be used instead as it has more books, better compatibility and also more object bounds as well)
-Console Books is now compatible.
-Utopolysts Item Sorting has a patch for compatibility.

Translations:
(Since I had to fix the bounds of a lot of items, those items will all be translated into English automatically. See the 'item fix list' file for instructions on translating it)
-Italian translation courtesy of Andre7890: Unlimited Bookshelves - Traduzione Italiana
-French translation courtesy of UchuNoSaru: Unlimited Bookshelves FRENCH
-German translation courtesy of Neakas: Unlimited Bookshelves - German Translation

*For modders (ignore this if you're not planning on making your own bookshelf mod):
-To create a new bookshelf mod that utilizes my script is very simple. Just rig it like the vanilla shelves, except instead of filling it with book markers, you only need one book marker at either end of the shelf, tagged with the keywords bookshelfbook01 and bookshelfbook02. It will still work if you fill it with book markers just like vanilla of course, but it will just ignore all but the first and last.