This thesis introduces GENMOD, a collection of subroutines which allow automatic geometric modeling of 3-D models for spatial links or linkages given a minimum amount of information as input. The subroutines utilize the CADCD (CADAM, Inc.) geometry interface software to enter 3-D data directly into the CAD/CAM database. Wire-frame and surface models are produced. Input is accepted from user created files with a standardized format allowing the GENMOD subroutines to be implemented regardless of the synthesis and analysis routines used. The realistic visualization of a mechanism during the synthesis and analysis process can help the mechanism designer to eliminate unacceptable linkage configurations in the early design stages thereby saving time and money. A complete description of the subroutines is provided in addition to sample graphic output.