Dilay us a 3D sculpting software.
The tools and brushes are limited but generally you start with a simple mesh like a sphere and then sculpt as if working with virtual clay. The sculpting can easily be mirrored across the center axis for symmetric objects. The tools are pretty straight forward, you can carve, crease, grab, drag, flatten, smooth and pinch your object into the desired shape. Nicely, you can also reduce, which enables you to dynamically reduce the polygon count of the mesh you are creating.
The other mode of operation is Sketching. Essentially you shape your base model using a series of spheres. Somewhat confusingly you need to delete your sculpt before you can sculpt. Now it’s mostly a matter of painting a series of spheres that will compose your base mesh.