To me it doesn't quite work having the hologram coming out of the top of the ball.

No other hologram in the saga is generated like that, they are either transmitted via droids (which is why I gave my first mock up an R2 style projector eye which swiveled around and pointed) or they are projected from flat beds usually with a light source underneath.

There is a ring of what look like switched off LEDs around the equator of the ball, I imagine that this would be used to project absent conference members into the seats (that might be cool in the conference scene too if one or two members couldn't actually be there they could appear as holograms, like the Jedi Council in ROTS).

The range could be adjusted to project a full figure like those we saw in ESB.

It wouldn't have to be the same actor either.

The message alert sound used to when the guy tells Tarkin that the Falcon has been captured could be reused (I liked the red incoming message indicator).

Good work fellas and a good stab at the sock removal there Jaitea.