I have a composition that has an animated camera and couple different layer items floating around in it.
I wanted to add another item, so I created it first as a static 2-D layer at a certain point in time in my composition, in the middle of a camera animation. When I activated the 3-D switch for that layer, it changed 'position' (relative to camera).
I was designing that layer item specifically for that moment in time, and desigining it from within the Active Camera view, so I need it to be in exactly the same 'spot' in 3-D space.
Is there a way to turn a layer into 3-D, and place it into 3-D space relative to where the Time Indicator is within a composition?
Not that I know of but if you get a hint on any of the other forums to which you posted the same question, please go back to all of them and post the answers.
I'm not understanding your issue completely but it's easy to adjust scale and distance from the camera to represent the same spot. Create your 2d item, make a copy of it. Convert one of them to 3d and then scale it to match the appearance of the original. I don't know how much experience you have with AE's 3d paradigm but scale is completely different from distance.
Yepp, David is right. Scaling and rotating the layer should suffice. Obviously you could also simply pre-render the other 3D pieces and then re-import them as a clip, then work your way from there using your new items...