  3-D printing moves beyond interactive 3-D graphics and provides an excellent
tool for both visual and tactile learners, since 3-D printing can now easily
communicate complex geometries and full color information. Some limitations of
interactive 3-D graphics are also alleviated by 3-D printable models, including
issues of limited software support, portability, accessibility, and
sustainability. We describe the motivations, methods, and results of our work
on using 3-D printing (1) to visualize and understand the Eta Car Homunculus
nebula and central binary system and (2) for astronomy outreach and education,
specifically, with visually impaired students. One new result we present is the
ability to 3-D print full-color models of Eta Car's colliding stellar winds. We
also demonstrate how 3-D printing has helped us communicate our improved
understanding of the detailed structure of Eta Car's Homunculus nebula and
central binary colliding stellar winds, and their links to each other. Attached
to this article are full-color 3-D printable files of both a red-blue
Homunculus model and the Eta Car colliding stellar winds at orbital phase
1.045. 3-D printing could prove to be vital to how astronomer's reach out and
share their work with each other, the public, and new audiences.
