Why is it so hard to talk to someone from Adobe. MY QUESTION is U3D still the only format to get 3D into a PDF. That being the case, how the hell do yop create it, or convert to it?

Hi,

Natively, U3D and PRC are allowed, but through a plugIn it is possible to manage almost all the CAD files formats, also neutral one, like STL, OBJ and so on...I am using Tetra4D Converter to doing this, and then convert it as 3D PDF, U3D, PRC or "neutral CAD formats" (Step, IGES, STL, X_T...).

If you have Cinema 4D then you can export out a 3D PDF by using www.4dpublish.com.  It uses the PRC file internally and supports textures and triangulated geometry. It also has a Page Designer where you can design the layout of your pages with buttons to control cameras and object animation within your scene.

You can create 3d-pdf's with Photoshop, PS can import a lot of 3d-files.
If you don't have PS, you can try with Meshlab, but most meshes need work to get correct results.

I'll ignore the first question and just jump to the second.

Using Acrobat DC, you can import U3D and PRC. You'll need to use another tool to convert from your source format to one of those. My recommendation is this...

https://tetra4d.com/tetra-4d-converter/