For Kicad 8, I created a folder ‘my_parts’ and copy these file in my_parts folder. Imported symbol and footprint (solder paste) ok. But not able to see 3D image in 3D viewer, only see flat solder paste. What am I missing?
Build in parts that come with Kicad display 3D fine.
What is lib file? Do I need it for Kicad 8?
With Kicad you need to create a 3D library.
Just as you imported the symbol and footprint into their respective libraries, you need to copy the 3D image into another, third, library.
When you have placed the 3D image into your library, you need to associate that image in that library with your footprint.
To do this, open your footprint properties, click on the 3D Models tag up top. Click on the path line and either type in the new path or click on the folder icon at the RH end and navigate to the imported image in your personal 3D library.
It will make working with 3D models easier if you use the (free, open source) STEP viewing program from “Open Cascade”