I see. I’d know how to draw but not how to have it recognised as a shape - never done anything like this.
I can’t find any tutorial for UE
The keywords for this:
https://www.youtube.com/results?search_query=ue4+gesture+recognition
But you may need to go digging deeper than YT, there’s probably tons of theory out there. It would need to be translated into UE environment. When I search the Marketplace for gestures, there seems to be some hits: Gesture Tracker VR
[…]Though this was designed with VR in mind, GestureTracker components are input agnostic and technically can work with any tracked motion, including from mouse and touch inputs.
You could buy a plugin, take it apart, see what you can learn. Or perhaps even use it as is.