UV Constraint:
|  | Make a controller that stick to one point of the model. You hereby can use this controller to constrain any object that you want it to stick to the surface of the model. Kind like the famous "Rivet" script. But the beauty is that it won't fly away after smoothing the model. The component it supports are: vertex,edge,face of polygon objects.
How to use: 1.Select vertex/edge/face of a polygon model. 2.Click button in maya shelf (If you installed all shelves of MGTools) or the same icon on MG-Constraint tool. 3.A U shape control will be generated. It is a nurbsCurve object. Now you can use it to constrain other objects. The UV constrainer is stable in translation and rotation. But in order to use this tool, your maya should support the hair system. The number of generated controllers is depend on how many components you have selected. Two vertex means two vertex constraint controller, one face means only one.