Freehand Sketching:

• Quick, simple transfer of information
• Conveys complex ideas visually without complex equipment
• Only requires paper and pencil
• Used onsite to resolve issues/explain ideas
• Examples include concept sketches, illustrating modifications to a design

Technical Drawing:

• Ensures projects are built to exact standards
• Technical drawing standards ensure clear communication and no misunderstandings
• Unambiguous graphical communication can transcend language barriers
• Gives specific lengths, sizes and tolerances
• Used for production of formal technical drawings for manufacturers

CAD:

• Quickly creates technical drawings
• Allows for quick collaboration and remote access
• Fast electronic communication of ideas
• Allows for more detail than technical drawings
• Can produce 3D models
• Can perform structural analysis
• Can quickly create complex shapes
• Linked to database of material costs to determine cost of project
• Can be used along with CAM/CNC/3D printing to create prototypes and models
• Examples include 3D drawing and detailed technical drawing of complex parts