Another ball rig! There are quite a few kicking about, but I couldn't find one with controls that behaved quite how I wanted, so here's my own take on things.

The default scene is all set up and ready to go, so just fire up the blend file and get started.

The rig has been designed to be flexible, and allows you to set things up in a number of different ways. There is a basic UI in the Tool shelf, please note that the sliders will change depending on whether you have the tail or ball controls selected.

• You can lock the squash and stretch control to the ball control, have it track to a target point or have it rotate independently.
• You can set the stretch origin to the centre of mass, or to the top or bottom tweak controls.
• The tail can copy the direction and/or magnitude of the ball squash and stretch, or align and stretch independently

From a rigging point of view the stretch controls have been separated using bones (no lattices here...). There's a little parent-child trickery involved to get it working, but it makes things like keeping the attachment point for the tail in the right place a lot easier. I can't think of any practical application for this right now, but it may be interesting to someone from a technical point of view. Who knows.

Also, as hardly anyone using Blender puts frame numbers on their work (makes crits difficult), that's been enabled by default for rendering. You're welcome.

That's about it (it is only a ball rig).

Note: This file has been re-uploaded with a less restrictive license. Go nuts.