Extruding along a motion path
by David on Mar.02, 2011, under Modelling
Check out this link..
http://www.stephenglover.info/animate-an-extrusion-along-a-curve-in-maya/
Simplified Steps:
1. Draw curve
2. Attach shape to curve using motion path
3. extrude the shape along the curve using Surfaces > Extrude[] (found under the surfaces drop down).

