rigid models
 

I was wondering how do i go about animating characters that don't deform as they move. e.g metallic characters - robots, pop-up toasters etc. Is there any way to build a character using hinges/ pivots of the kind you see in real life and then make them solid so that the geometry can't "pass through" other geometry? surely then the model would work without the need for a skeleton.

There are lots of ways to animate. Most popular to use are IK, FK or SDK...

<what did he say, i wish people spoke english on this forum:p>

FK = Forward Kinematics
IK = Inverse Kinematics
SDK = Set Driven Keys

Both IK and FK need to have geometry bound to a skeleton, but SDK does not and practically anything can be animated via SDK and Custom Attributes. There are two standard ways to bind, they are rigid and smooth, both produce different results. Have a look at the Maya files for a full explanaion of what each option is and what it does.