Hello!
Dynamic masks are an existing request: [Request]: More advanced collision masks - #2 by Nttgames
and an alternate take of one-time mask creation: [Request] "Magic wand"
I think the primary reason why dynamic masks aren’t possible currently is due to not allowing for concave collision masks. There is a larger discussion on the github and in the above threads on that.
However, as this is an existing request elsewhere, I’m going to close this thread out.