 So, no matter where you paint, your model just never seems to have the perfect shape. Not a problem. To make a shape key, pose your model in an area that you are not happy with. Go to object mode, click your mesh, and in the modifier tab, under weight paint, make sure that cage and edit are on. Then under object data, and shape keys, press the plus button twice, name the key after the area you're fixing, drag value all the way up to one, and from here if you are a sculptor, you can go to sculpt mode and do your thing. But if you're doing low poly game design like me, it's much faster and easier to do things in edit mode. Once in edit mode, move the points into the shape that you want them to be during this pose. When you're done, you will notice that you can control when the key activates by dragging this from zero to one. And of course, we want to automate this with a driver, so that it triggers when the pose happens naturally. In my case, I want the key to activate when the leg bends backwards. And if we look here, seems like that is controlled by the hit bones X rotation. And now that we have a trigger identified, you know the drill. Right click the shape key, add driver, set object to armature, set bone to hip, type to X rotation, mode to quaternion, space to local, and type this, you're done. Now if you do that and this number is not equal to one, that means you need to go back here and change this part of the equation until the output is one or close to it. Now you can see that as the hip rotates back, the shape key kicks in and we get the beautiful form we need. This right here is just my basic exponential formula. Which means that it's weak in the beginning, but gets stronger as we approach the target pose. Hope that helps. If you enjoyed this video, please don't forget to like, subscribe, and ring that bell. Hope you have a fantastic day and I'll see you around.