Fundamentals and a new way to look at collision margins for anyone using Bullet physics engine: devs, game asset creators, users of 3D packages with Bullet built-in (Blender, Carrara Pro, Cheetah3d, Cinema 4D, Dynamica, Houdini, Lightwave 3D, Maya, Modo, Poser, Softimage, thinkingParticles) or any other (in-house ;P or otherwise) software.

Hopefully this answers some questions and seeds some new ideas. But please do not PM me any more questions! I cannot answer all of those PMs, sorry. Use the appropriate forums if you have questions. Thank you.

Collision Margins: 0:57
Sphere: 2:53
Box: 3:50
Capsule: 5:15
Cylinder: 5:54
Cone: 6:26
Convex Hull: 6:57
Details, Convex Hull Computer and Exploiting: 7:39

Compound Rigid Bodies
Compound Table: 14:27
Compound Primitives: 16:15
Hierarchical Approximate Convex Decomposition Hand: 18:57

Margin Tricks
Rigid Tape: 21:45
Bevelled Cylinder: 23:48
Manual Convex Decomposition Pipe: 25:58
Manual Convex Decomposition Curve: 29:10
Manual Convex Decomposition Bowl: 33:17

See my previous video's description for a link to download the free StudioPhysicsDemo scene file for Blender (and forum link):
http://www.youtube.com/watch?v=hM3wke1mVgE&hd=1

Bullet (free! source code): http://www.bulletphysics.com
Blender (free! 3D suite): http://www.blender.org
"Compound Parent" patch for Blender:
http://projects.blender.org/tracker/index.php?func=detail&aid=34579
Example convexHullMarginMesh C++ code to generate margin meshes:
http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=17&t=8995#p31234