This thesis describes research into the use of interactive methods to create three-dimensional drawings for the conceptual phase of engineering design. Discussion on developing an efficient user interface for conceptual design and techniques for creating three-dimensional sketches is provided. The work also includes design and implementation of a user interface for creating simple three-dimensional drawings. A program was written to implement the creation of three-dimensional drawings in an oblique view with a graphics tablet and multi-button cursor. It allows the user to sketch in a way similar to that done on a piece of paper. Three-dimensional data is generated from two-dimensional input. Depth cueing for the sketched object is given by interactive orthographic projections onto primary planes and rotation about different axes. The menu and display makes use of icons and color to improve user familiarity and feedback. Only straight line drawing, which is represented in arrays of end-points, is implemented. / M.S.