3D Printed Model or 3D Printer File for New Zealand

I need a physical 3D relief model of New Zealand. This must include North Island, South Island and Stewart Island. Relief must be proportionally correct with the length and width. The physical length of the model is only 30mm (3cm) long. This will be used to create a mold from which casts will be made. As this is still a concept at present I would be happy with either a completed 3d Model or a 3D Printer File that will allow this sized model to be printed locally. Land Information New Zealand (LINZ) possess files which with manipulation apparently can create a 3D Printer file however I do not have the expertise for this.