I've made a four-armed demon out of two V3s but I need a way to make parts of the left and right collars invisible. Is there a way to do this, maybe with the Grouping Tool?

Sure. Just hit New Group, give it a name, select the facets you want, then (most important) hit Assign Material. Give the material a name, then you can treat it like any other matl, and make it transparent. Here's a quick example from selecting two facets of the Ball.

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The grouping tool is the way to go. Select the polygons you want to make invisible in the Grouping Tool and assign a new material (name the new material Invisible). Then change the Invisible material (P5 material room or P4 material dialog) with specular and diffuse colors black, specular value zero, and transparency at 100%.

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Sorry, crosspost with ockham.

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Awesome, thanks guys!