1. Create a new document in Adobe Photoshop.

2. Set the dimensions of the PS doc to the folding or 3D object dimensions where it will be applied onto.

Make sure to use 72dpi instead of 300. 

3. Import a document image into Photoshop.

In this case we have an transparant background and black content.
Black content will not receive a bump when visualised.
In order to make this work we'll need to make everything that is flat black.
And all other should be grey or white depending on the complexity. 

4. Select the correct layer and click menu Filter > 3D > Generate normal map. 

It could that at this point your PS doc holds multiple layers.
In case you do, it's recommended to have them merged together prior to generating a normal map.
 

5. Depending on the size and computer performance it might take a little bit to render.

6. Once completed, a virtual 3D effect is shown inside a popup.

If the results looks nothing like you would expect it to be, make sure to check step 4.

7. Additional changes can be made to alter the reflections and thus the general outcome

8. Click OK and export this image as a png file.

9. Upload to the Assets Management, once done it can be selected for use.

The example shown here is how it looks like in the Folding viewer