I'm no expert. I hope mine is useful to you. Sharp corners, soft corners, maybe soft and hard. There are common default brushes, and the soft ones are brushes that are gradually spread out, which are used for diagrams that require coordination in transition. The hardness nib is a straight pen with no gradual edge, which is used for drawing with special shape and clear outline. The second, slimming, I think there are many ways. PS is extensive and profound, and we have many methods. As long as it can achieve the effect, choose what you are familiar with and like. If you feel good, you can also draw a circle with the pen tool. I have never done slimming, even if it is the design of a photo studio, but the pictures I usually make give people an unreal feeling. First, the overall slimming, check the material, use mobile tools, deformation, that is the whole, the effect is not good. Second, local deformation, mirror filtering, liquefaction, and several tools inside will do. Some people will say that my method is not good. Different people have different opinions, and different people have different opinions. Watch the operation. Third, visual artifacts, when choosing materials, make the thinner part smaller and bleed a little more (terminology: the selected part is smaller than the original image, and discard part of the original image), and then adjust the edges appropriately, so that excessive colors will show better results.