so if u didnt already know in 1.9.5 the enchantment table lets u upgrade weapons and tools. if the enchantment table is close to bookshelves the higher level enchantments r available so i am building a redstone room with enchantment table in the middle and two rows of bookshelves on all sides the table only uses books within a 1 block radius so in first position no bookshelves will interact in order to get low level enchantments. first lever will bring in 1 row of bookshelves for medium lvl and the second will bring in the 2nd row for high lvl.