First learn to model and rig human models. Then correctly rig face.
That face creator is not much more than just moving bones around and changing material.
From programming point of view it is not that complicated (just lots of tuning and trial and error adjusting)
Its hardest part comes from fact that one needs to be good programmer and artist to make decent face creator.
Thank you for replying
I generally know about modeling and rigging but because I am coming from an artist background could you go into more detail with specifics? Thanks.
Ahh then look into morph targets in unreal: FBX Morph Target Pipeline in Unreal Engine | Unreal Engine Documentation
Then make bones for major face features and move them like described there: Transform/rotate bones in animation blueprint - Skeletal controls not working - Character & Animation - Unreal Engine Forums
You also need to learn whole animation blueprint part: https://docs.unrealengine.com/latest/INT/Gameplay/HowTo/CharacterMovement/Blueprints/index.html
Also some UMG is required so you can make gui:
If you want to get a pretty good idea you can use this HERE
It’s a very good starting point