The is a broad category that highlights creativity and the engineering process.  Students can present their final invention, which should be physical construction.  Included in the presentation will be an inspiration for the invention and expectations for future applications and improvements.  The process may include blueprints, CAD work, or a sketch or technical drawing (appropriate for the grade level).  A prototype is not required but it is encouraged and should be documented with images.  A work log can be used to show trial and error and to document the engineering process.  Materials are limited only by what the student can access.  3-D printing is acceptable and encouraged when available.