Blueprint Help Car Configurator Paint Material Slot

Hi guys, currently working on my own car configurator using the template from the UE4 A5 configurator sample: he states that he’s added in that material slot to the blueprint but doesn’t show how that is done.

Is anyone able to show me how to create a material slot within a blueprint to appear in the details panel so that I can use his method for the variant paint switch.

an example of my details panel compared to his:

image

As you can see he has the paint material slot in his whereas I’m not sure how to achieve that in mine.

Any help would be greatly appreciated.

Thanks in advance.