Thanks all I appreciate the comments. jchaos it was the hat that really set the character of the model. It's from the Empire greatswords kit. I tried sculpting a pirate hat and I was happy enough with it but when I tried on the empire hat that was it.
Glad you like them Geep thats probably the last of them I'll be able to cast the molds have started to warp so it's very difficult to get a proper cast done.
I use a 2 part RTV silicone to make the mold. The molds are done in 2 pieces, the green is set into plasticine with one half exposed. A box is built around the piece (i use lego for the box) to hold the silicone while it sets. The silicone is poured and allowed to cure for 4 to 6 hours. The plasticine is removed from the other side and the mold is coated with release agent (otherwise the silicone would just stick to other half and trap the green) The box is reset and the other half is poured and allowed to cure. Thats the mould done you need the cut pouring channels and air vents into the mold.
Here's a picture of my Rhinox mold:

The protruding bits help to align the mold and hold it together while casting.
I cast in white metal using gravity casting. I don't have a centrifuge and couldn't justify the cost, I lose very little detail gravity casting but then I've had lots of practice. I've tried resin but it's not great at this scale and I like how metal sets very quickly. The molds are only temporary and will warp/burn out over time.
Hirst arts has a good tutorial if you want more detail.
http://www.hirstarts.com/moldmake/moldmaking.htmlI still haven't based the Slave giant but here he is prebasing:

I keep getting distracted by other things (Damn you God of War 3!). I've been painting some warhammer scale Empire stuff this week so nothing else has been done. I have the shortest attention span and just seem to keep jumping from project to project. I have no idea how I ever managed to paint 4500 points of Daemons but I do have another 3000 points to paint

No idea when my next update will be as I'm really liking working on the larger scale at the moment