2019: Generate UV's

Not much news. Well, there is a new 3D function in the Photoshop 3D menu, Generate UV's. It will unwrap UV maps for your 3D model. If you do not use this before exporting the file to f.e. Sketchfab, skins will be absent in your online model.

* Create or open a 3D model in Photoshop
* 3D > Generate UV's
* 3D > Export 3D Layer
* Choose for exporting as Collada
* Export
You made a DAE file with its skins in PSD's. You can work on these PSD's of course. Opening the DAE in SketchUp produces a kind of wire model, but you can work on it.

* Create or open a 3D model in Photoshop
* 3D > Generate UV's
* 3D > Export 3D Layer
* Choose for exporting as Collada
* In the export dialog panel at the bottom choose for PNG
* Export
You now made a DAE file with its skins in PNG's. This you can open as a complete object in SketchUp, and use it to send it to Sketchfab.