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Create a 3D model of bicycle chain links using only BRL-CAD tools.

BRL-CAD provides several ways to model 3D geometry including a graphical tool named mged, another named archer, and various ways to create geometry using scripts. We use 3D models for development and to showcase our features. You can learn the basics of 3D modeling in just an hour or two.

References:

• http://brlcad.org/wiki/Documentation
• http://en.wikipedia.org/wiki/Bicycle_chain
• http://upload.wikimedia.org/wikipedia/commons/b/b0/Rollenketting.gif
• http://pardo.net/bike/pic/fail-004/000.html
• https://www.google.com/search?q=bicycle+chain&tbm=isch
• https://www.google.com/search?q=bicycle+link&tbm=isch
• https://www.google.com/search?q=bicycle+drawing&tbm=isch

The model should have regions defined for each part (each separate piece of metal becomes it's own region) and no overlaps (use rtcheck and/or gqa commands to verify). Model it natively using any of BRL-CAD's tools (i.e., don't model it in something else and import) using 3D primitives and Boolean operations. Create one top-level combination to group everything together. If you base your design on an image you found, please cite your sources.

SUBMIT a PNG image, your geometry in BRL-CAD .g file format, and a text explaining how&why you made your model the way that you did. You can run "rt -s1024 -o your_rendering.png your_geometry.g your_top_level_object" to create a PNG rendering of your model.