Share 'random extrude + offset'

hi guys, I obtain a crazy voronoi 2D on a plane and now I would to extrude this closed curves with a random form but in a range of 15 to 60 (centimeters).   plus, i would that this extrude forms are offsetted because I don't want that this volumes are in touch...a little distance just for render shadows and a best lookin' thing!   can you help me with an easy algorithm?   thanks a lot