I made a VDR Heavy walker for the harlies. Unfortunatly, it only has 2 heavy weapons because of lack of good spots to put other weapons, but I still think it is okay, although you could put one on one the arms, and the only advantage of this being a heavy model (just a few more points than medium) is that the back armor doesn't have to be 9 or the front armor 13 because heavy walkers get 1 more armor than mediums.
It uses the Eldar Towering Destroyer Knight Model.
Harlequin Vexer (if you got a better name, tell me)
WS: 3 BS: 4 S: 4(
I: 4 A: 4
Front: 14 Sides: 12 Back: 10
Weapons: Dreadnought CCW x2, Targeter Pulse Laser, Targeter Scatter Laster, 2 Flamers
Eldar Field on all sides, Ferocious
Total Points: 335
It looked pretty hard to take off the scatter laser and make it look good, so i kept it on. Also, S: 6 isn't that bad, because stuff below T4 are automatically killed with no saves.