Create Blueprint Class from Object, Instances

 Creating a Blueprint Class from an Object

   Add a sphere to the level, select it. Over in the Details window for that actor, the name of the sphere should be 'Sphere'. Over to the right of that you'll an '+Add' button, just right of that is a details button that when you hover over it, it should say "Converts this actor into a reusable Blueprint Class that can have script behavior". Click that button

   A window will pop-up that says "Create Blueprint From Selection" at it's top. We want a "New Subclass" so we can just leave it all as is. At the bottom, we can give a new name. Apparently, it's custom to prefix a new Blueprint Class name with 'BP_'. So here we can name it BP_Sphere. Press the "Select" button at the bottom.

   A new Unreal Editor window will pop-up for the newly created BP_Sphere. You can, if you want, dock that new window with the first Unreal Editor window to keep it all together. Then go to your Content Browser and in the Content Folder, you should see the BP_Sphere Blueprint Class that we just created.

Instances

   Drag that BP_Sphere Class from the folder to the level scene, it will make a new instance/copy of that blueprint. Now, go back to the BP_Sphere window editor and change any of the BP_Sphere component detail properties, it should affect all instances of the BP_Sphere in the level. On the left side in the BP_Sphere window editor in the Components window pane, you have to select the components to see the detail properties of the sphere. So under the BP_Sphere, select the Static Mesh Component. Then, go to the right side in the Details window pane, Try changing the material property and see how all the BP_Sphere instances changed to the new material.