Some ways to create models of solids

• Hand build point by point - normally only used for simple items such as a cube
• Hand build using a 3D paint style program
• Directly from the mathematical formula - again relatively simple items such as the quadric surfaces (this will give you a sphere)
• Sweeping out a volume from a 2D item (VRML lathe)
• Blobby objects
• Parametric representation of sheets (often ruled surfaces)
• Bezier surfaces (and building surfaces from patches)
• Constructive solid geometry (CSG)
• Deformation of existing models (morphing is related to this) ( an example -VRML )
• octrees (and quadtrees for 2D)
• fractal generation ( Kotch Snowfake ) a gallery
• or input from instrument (e.g. MRI), image , 3D scanning (by D. Huber ) or a computer model