Well look at that...I forgot to post the traditional solution!
Label the coins A, C, D, E, F, I, K, L, N, M, O, and T. Weigh them according to the following statement:
MA DO LIKE
ME TO FIND
FAKE COIN
i.e. weigh MADO vs LIKE, METO vs FIND, and FAKE vs COIN.
Draw up a table of weighings vs coins (so 3 columns and 12 rows) and put the results of each weighing (either tilts left, tilts right, or balances) into it. From this, you can tell which coin is the odd one, and whether it is heavy or light.
Label the coins A, C, D, E, F, I, K, L, N, M, O, and T. Weigh them according to the following statement:
MA DO LIKE
ME TO FIND
FAKE COIN
i.e. weigh MADO vs LIKE, METO vs FIND, and FAKE vs COIN.
Draw up a table of weighings vs coins (so 3 columns and 12 rows) and put the results of each weighing (either tilts left, tilts right, or balances) into it. From this, you can tell which coin is the odd one, and whether it is heavy or light.
