Start by asking him what he thinks would be representative of NZ and what would make her happy!!
Perhaps he could give you some pictures and then you could print them on fabric .... her home, her family, places they've been to and things they have done as a couple in NZ, etc.
Include a map of NZ with a star for her home. Maybe a family tree, if she's homesick for her family.
Get him very involved .... and you'll be happier, and so will he .... and she will be overwhelmed at the co-conspiratorial results! :)