Blender has had shape keys for some time. They are a common part of most 3D models. But, since we can’t import Blender generated shape key information into Second Life™, the keys have not been much use to us. However, they can be used to make different size dresses, shirts, hands, feet, and whatever along with testing whatever we make.
AvaStar added tools for the use of shape keys to help in making standard sizes of our creations. Now Medhue Simoni has made a video showing what can be done with shape keys and how they work. He doesn’t say much about how we use the keys with things we are making for SL, but he does mention an important point: we will likely be able to use shape keys in the Next Generation Platform, SANSAR.
If you are interested in using shape keys to more quickly make standard size clothing items, refer to the AvaStar tutorials on Machinimatrix.org.