@kagazwala said: Chri Sorry for being a nerd, but I really didnt get what you trying to explain %(#0000FF)[hi kagazwala Have you try my example kagazwala 3 with sketchyphysics ? Take a look on the next vidéo. concept when two parts are common parts, they repel i think it's the major probleme of your scene . take a look and test my example kagazwala 4 with sketchyphysics chri] kagazwala 3.avi kagazwala 4.skp [image: pkKX_kagazwala4.png] [image: mKDp_exampleofconcavepart.png]