Creating the base object
Since the editing tools can only work on existing objects, the first thing to do is create a new object:
Start Blender and select all objects (A) and delete them (X).
Then, add an icosphere (Shift + A) through Mesh | IcoSphere.
Icospheres differ from normal spheres in that they don't bunch up at the poles. This will work out better for sculpting. But if viewed from the top (Numpad 7), the icosphere is not symmetrical from left to right. To fix this, follow these steps:
Rotate (R) the icosphere 90 degrees along the Y axis (Y).
To make the icosphere into a disk, scale it (S), constraining to the X and Y axes (Shift + Z), to about a factor of
5
.When the disk is the right shape, apply (Ctrl + A) Rotation & Scale.
Tip
Applying rotation and scale doesn't have any visible effect on the model, but it will affect other things, particularly those related to the sculpt tools. Before applying rotation and scale, the object you see was actually another object modified with rotation...