This chapter deals with three ways of realizing solids from surfaces. After all, a solid is made up of pieces of surfaces on its boundary; therefore, in general, it is natural to piece together surfaces into a solid. On the other hand, the outer parts of a solid can be extracted for a number of bounding surfaces. The chapter presents a very useful tool for filling surfaces. This is a very useful tool in the manufacturing industry. The chapter explores a generalized methodology for free-form surface design. In SolidWorks, there are at least two ways of creating a free-form design: extracting an existing surface from a three-dimensional part and creating a free-form surface and creating a free-form surface from scratch. The second method is not popularly used because the users of this method should be fairly conversant with the knowledge of how standard surface modeling methods work.