Fade out model opaque to transparent

Is there any way to fade out a model from opaque to transparent? The only way I thought of was creating and applying a new material every millisecond with less and less alpha value.

Yes.

No… just set a different color with a different alpha value.

If you want us to be more specific then you will have to provide more information.

I import an obj file from blender that has a PNG attached. I don’t have any materials set to it either. What other info do you need?

Well, you do have materials set to it… or you wouldn’t be able to see it. They just aren’t materials that you set.

Find the geometry(s), get the material(s), change the color to something with a different alpha value.

Is it a lit object or is it unlit?

Either way, things to look at:
-javadoc for scene graph visitor
-javadoc for material
-material tutorials… especially the link that takes you to the material parameters for the standard JME shaders.