I got the first Wraithlord done. Not awful for a first attempt, especially with incredibly crappy old modelling putty.
After sanding the head and leg down, there were still a lot of grooves and fissures, so I coated it in ultra fine crazy glue to make the surfaces smooth.
Buddy is overjoyed, and actually thought it was an original head that had been paint stripped in something overly nasty, so that was nice.
I haven't told him about the Wraithseer yet, which I'm working on now.
edit: One of the things I learned from this is to not handle the putty until it has a few minutes to dry on the outside. Trying to handle it right out of the tube gets your hands covered in toxic nastiness. If you wait a few, the outside becomes dry to the touch and you can much more easily shape it.
Worry not about Chaos; it is the used 40k market that shall be thy temptation.