Well, maybe they were right.
Either way, I'm currently working on a Chaos/Nurgle team using a bunch of models, specifically the Stormcast Eternals, as Chaos Warriors.
I thought it might be fun to blog the progress that I make, both for posterity and so I can show these nay-sayers that anything is possible!
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DAY ONE
So I received my chaps today, and there are a few snags that are obvious from the start.

1. Their shields are hooge, and are fused with the arm.
2. Their bases are also huge.
Still, all is not lost! some of the models don't actually have shields, and instead have these great whacking two handed hamemrs. These seem like a prime target for conversion.

I snip the weapons off of them and here they are.


Its worth stating that some of the weapons have ribbons or other accoutrements, be aware these are often fused with the arms or legs.
I used green stuff to add a few tentacles and whatnot. Can't have them all shiny and polished, can I?
I only had 3 of these guys, so I needed to try my hand at shield-trimming. I chose this guy:

and, with care, it seemed to work. I fished out an old Minotaur that I'd tentacled up and some Kings of War ghouls to use as rotters.

So far so good!
The fella with the shield had a bit of mess on his shield forearm, so I used green stuff and a spike off an old chaos land raider to give him a punching spike. I also made his other hand a tentacle, as it looked unusual in the pose it was in. I realise I don't have a picture of him alone, for some reason, so I'll update with one once his tentacle arm has set. He's currently lying in a very strange pose with some halflings holding up his arm.
Now, the bases...
After a fair bit of experimentation, I reckon the drone flying bases from 40k are perfect. Not too small that the model looks weird, and not bigger than a BB square (just!).

I contemplated having it round-side down. It would be easier to stick the now baseless sigmarites on them, plus swivelling and moving might be smoother, but opted for the round side up in the end.

He's using Blue Tac at the mo. Once I get enough bases I'll stick them all onto them. I can't decide whether I want to leave them clear or not...
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Anyway, that's all for this update. I'll post another when the next load of bases arrive!