Since the new Cryx character Helljack 'Nightmare' will probably cost £25 to £30 I thought I'd have a go at converting my own on the cheap. What follows is a diary of my progress.
Day One: Today I bought a badly built second hand Slayer Helljack for £2.00 from my local gaming store and retreived a 50mm base from my bits box. It's missing it's head and arms but it'll be a good starting point for my project.

I've dissasembled the Slayer and put it in some stripper to strip off the paint and Milliput. I'll come back to it in a few days.
Day Two: I've cleaned up the Slayer parts and reassembled them. The base is made from bits of roof slate (thank you strong winds) and bits of 'garden' stone ('borrowed' from other peoples front gardens) greenstuffed and superglued to the base. The gaps between the slate are filled with builders sand and the rams head is a plastic Citadel skeleton warrior head. The left leg is pinned through the slate to the plastic base with aluminium rod.
Now I just need to aquire some arms and a head.
Day Three: