Yeah, just create a sprite with the same anim frame throughout the animation and set the collision mask differently on each frame. Then when you want to use a different mask, switch to that anim frame.
Cheers, unfortunately this won't work for me as I need the circle mask. Making my own collision mask by points is nowhere near as accurate as selecting the circle mask from the drop down menu. It's okay I got around it by spawning another instance of a identical shape with the correct mask and I just show and hide while the game is on the Thanks for the Input