PW2 - render refraction in air glass & water?

Hi all,

I'm trying to do some sample renderings to illustrate the refraction of light in a plastic model that has air on one side and water on the other. This seems difficult to do in SW for a few reasons.

I've created an assembly with 3 parts, essentially my plastic part embedded in a core/cavity block whereby the core is defined as water and the cavity is defined as air.

I've set all 3 parts to 'plain glass' full transparent etc. with the proper indices of refraction:

air = 1.00029; water = 1.333; acrylic = 1.499

I've then put reference decals on certain faces of the blocks to be able to observe the refraction.

The main 2 problems are:

1: Can't really embed the 'camera' inside the air the way I want to. 2: The strange 'polygonal' shapes visible in a rendering when to solid bodies share a coincident face.

Any ideas for improvement would be, as always, greatly appreciated!

Thanks,

Zander