Miss B...

A) Geometries are not exclusive to figures. Many (most?) props have geometry files. And I looked in the libraries anyway... wasn't there.

2. If there wasn't an .obj file, why would Poser ask me where it is?

And in conclusion... me fix. Made a modified render dome type tingy in Poser; Loaded a sphere, flattened the bottom w/ a magnet, used the grouping tool to invert the normals, scaled it up REAL big, exported it to a safe folder as an .obj, used a script to compress the .obj to .obz, moved it to my Geometries folder, fired up Poser & Bob's me uncle :D

WARNING!

This user has been known to swear. A LOT!