Here’s an excellent model to practice some sculpting with Fusion 360. It's an adorable ghost that can be 3D printed.
We’ll start by first jumping into the sculpting environment. When you first open up Fusion 360, it defaults to the modeling environment. Click on the Create menu on the toolbar and select Create Form or simply click on the purple cube icon on the Create menu. You’ll now notice that your menu items have changed and the icons now mostly have a purple color. You should also see the word “Sculpt” instead of “Model” on the upper right corner.
Click on the Create menu and choose Plane from the menu. Select the bottom plane (in my case it’s the xy(red, greed) plane) and starting from the origin click to begin creating a plane. Click again to complete the plane. The size doesn’t matter at this point because we will enter the dimension in the dialog box that appears. Enter 50 for Length and Width, 5 for Length Faces and Width Faces, Symmetry - None, Operation - New Body. Click OK.
Next, we’ll turn our rectangular plane into a rounded rectangle by deleting all of the corner vertices. Simply click to select the individual vertices and click Delete.