1. Export both parts of your helmet seperately as object files.

(Make sure to choose the correct import/export scale. I import stuff from Poser into Wings3D using 20.0 and export using 0.05)

2. Import the two objects into Poser one by one.

3. Open the Hierarchy Editor.

4. Rename the lower part "Body".

Make the upper part a child of the Body. (Simply pull the name of the upper part over the "Body" in the Hierarchy Editor.)

5. Select the Body (!) and click "Create Figure" in the Hierarchy Editor. Select a name.

6. Open a new scene.

7. Load the new figure that Poser created from the "New Figure" folder of your Poser root library.

8. As your figure is supposed to be a hard-shelled object that does not deform, select both figure parts and disable "Bend".

9. Open the Joint Editor and edit the center of the moveable upper part, so that it will properly "open" if you dial xRotate. (You can also rename xRotate to "open" afterwards)

10. Add textures and safe your finished helmet figure once again to a library of your choice.