Availible as a plugin to XSI only This is a practical muscle system for character rigging. Found via forums in my research on the subject it is rated as one of the better third party plugins.

The plugin is free which means there is little in the way of support, documentation or tutorials. The system has bugs which have been refined over the versions but is still considered unreliable to industry standard.

Its not the most feature-full or fastest either method for creating muscles working as an automated version based on a system not disimilar to creating shape driven muscles.

But it should work and allow for as much "rigging on top" as possible, while keeping the workload of muscle system generation down to a minimum. [author]

It will builds muscles in placed on top of user drawn curves. The orientation driven muscle flexing operator scales the muscle belly, and pulls it toward a givne tendon, based on the orientation of a chosen target object. Both scaling and pulling can be turned off independantly if desired.

The system can be enveloped using xsi standerd tools, using the tendon and belly nulls as deformers along with the bones. This is the simplest method and provides satisfactory results.

The system is very specific and requires direct instructions to work for example the following. "IT IS VERY IMPORTANT that the muscle be created in place in the bind pose. If you repose your muscle system and then try and apply a cage deform in the new pose, you'll find the muscles are weighted in their original modeled position, not in their posed position"

Trial and error plays a large role in getting the required results. To complicate and slow the system down further A third more complex way to appraoch this is to use syflex. helping you to achieve the realistic skin slide and wrinkles. At the cost of performance and syflex usability.

Controls are created the same way as the custom parameter sliders found in syflex making the usability simple yet univiting.