Creating an anvil in minecraft - what's the trick?

nobody mentions the repair cost creep. every time an item goes through an anvil the next job on it costs more, and once it hits 40 levels it just says too expensive and refuses. so merge your books together first and put them on the gear in as few goes as you can. the anvil chips with use as well and eventually breaks, so don't build anything fancy around one. longer term, get mending on whatever you use most. it repairs the item from xp orbs as you play, so it never has to go back on the anvil and the cost stops mattering. villager librarians are the reliable way to find the book.

3 blocks of iron across the top row, 1 iron ingot in the very centre, 3 iron ingots along the bottom. that's 31 iron in total, so it's a pricey one early game. worth it though if you're repairing gear or renaming stuff.