Easiest way to make enchantment table?

fifteen bookshelves is the number you're after. that gets you to level 30 enchants, and anything past fifteen does nothing. they have to be one block away with nothing between them and the table, even a torch in the gap blocks it.

book top middle, a diamond either side of an obsidian in the middle row, obsidian across the bottom. four obsidian, two diamonds, one book. crafting it is the easy half though - on its own the table caps out low, so you want bookshelves around it with a one block gap between before you see the good enchants.