Postcards with "Tianjin" written on them will do.

Oh, I'm sorry.

Actually, that’s not what I meant. If food is not good, crafts are not good, and things that are easily broken are not good, there are not many choices.

But since you asked, let me give you a clue. In addition to the commodities, Tianjin is also famous for its "Five Avenues Western-style Buildings", which are really the most unique! You can go around this subject and see if it's possible to get some souvenirs. Actually the postcards are pretty good.