Here's my Chaos Space Marine Aspiring Champion by Games Workshop which I've painted up in an A Thousand Sons Chaos Chapter color scheme.
I actually painted this guy for a painting competition at my local store for which I won first prize. I haven't painted many chaos space marines so it was a good way for me to extend my skills.
I tried to incorporate a lot of organic elements into the model, such as the fleshy demon bits emerging from the armor, the bone dagger and the living axe. I feel that these aspects merged with the technology of the space marine armor bring a more supernatural and menacing vibe to the model.
If I were to paint him over I would probably put emphasis on shading in the power armor as I feel for an 'evil' guy hes a little to bright.
Overall I think its a great sculpt by Games Workshop and I love the detail and posture.
Enjoy.
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Till next time.
~James