Well, to beef up AC, start with Int 18 or 20, that will start you off with AC 14 or 15. Take Staff of Defense class feature, that's another +1 AC. Take Unarmored Agility or Leather Armor Proficiency, for +2 AC. So that's as much as AC 18 at lvl 1, as good as plate armour without a shield. Adding in magic items, there's the Staff of Ultimate Defense, lvl 3 magic item, +1 AC per plus if you have Staff of Defense class feature. Magic robes or leather armour will beef up your AC as well.
If your eladrin has Str 13 & Con 13, you can take leather armour proficiency and then chain proficiency and Eladrin Chain is a good item to have because if beefs up your teleports.