The newly discovered photo of the back of the communicator showed that I still had some basic details off on the rear delta piece. In reality it’s a fairly simple plant-on made from a 2D profile cut from sheet/plate material, with the right portion brushed/textured differently - no three-dimensional fillets or chamfers of any kind.
I initially based its size, shape, and details on the delta incorporated into the two phasers, and when that was proven incorrect by the blue-print style animation released a few months ago, I simply increased its size and adjusted the shape of the curves a bit to match. Now that we have an actual photo of the back, the detail is much easier to make out.
I’ve added a new “accurate delta.stl” part to the first post - this revised design includes sharper points on the delta, a smaller star, and an overall thinner profile with only a very slight 0.005" step down to the right portion of the delta (just enough to provide a guide for masking when painting). I also eliminated all fillets on edges as the photo shows it to be a simple 2-d shape. It’s difficult to tell how thick the delta in the reference image is.
Due to the thinner nature of the part, the delta is no longer practical to use with the ipod button mechanism, and the recesses on the back of the mounting stud have been deleted to improve printability. I did update the original “delta.stl” with sharper points, but that’s the only change to that part.
In addition the three holes below the delta in the “lower shell.stl” part were enlarged and repositioned slightly.