I would like some feedback on these mouths. I've tried to draw the mouths and then add the contours on top of them, but as soon as I turn off the cross-contours' layer they look a bit flat, or is a wrong feeling?

given the scale of the mouths compared to the cylinder, you can get away with pretty much the same mouth in every angle in this way. I'd suggest to draw much bigger mouths so they have to follow the f