You will likely not be able to print any Warcraft 3 model without manual editing.
I don't think there is a single model that is solid.
1) People optimize models and remove polygons that are not visible.
2) Many models contain geosets that are not solid, like capes, spherical-looking things that use billboarding, etc.
3) Many models contain geosets that are not physically attached and have a space between them (e.g. arms not fully attached to the shoulders).
I do remember at least two users posting models they printed, but it was a while back.