This example uses a basic cone. If it was created as a solid, and you try to node edit it, you will see that it cannot be selected. 
- Select the cone and open its Properties (see Object Properties). On the 3D page, select TC Surface.
- Select the cone again, and click Explode (or select Format / Explode).
- You can now node edit the cone nodes.
----Note: You also could have exploded the original solid object twice to obtain an exploded (node editable) surface. - Drag individual nodes to change the shape of the cone.
