Actor moving when I dont want it to

ElemetApps

So I have a game ware you draw, so its a lot of actors spawning. And I want a square to be able to break through it and another actor (say it is a ball) I dont want that to be able to break through the line. Movable is on for the drawing actor and the density on it is crazy high, and the ball has a low desity. So this helps a little but the line that I draw gives a little to the ball when it collides. I know you cant turn movable on and off while in game play, and I cant do it by spawining another actor that has movable off and replace the drawing actor with it because thats way to many actors being replaced at one time. So how can I make it to ware the square can break through the drawing actor and the ball cant at all.