The Screamers are a bit of an odd model to paint. Well, I guess they're a bit of an odd model, full-stop. The difficulty with painting them, though, is judging how much detail to go into.
In some ways they are super-easy, because they are effectively just blobs of energy spawned from the Warp, so you could do them as a single colour, but if you look closely, there are loads of tiny details to the model itself.
I opted for something in-between. I made sure that the models featured a few of the details that make them so cool, but I didn't go to town completely on them.
EYES! THE EYES!!!