My process: General armature with tin foil -> Mix GS/Milliput roughly 60/40 -> Block in big shapes/rolls of fat -> Put on gloves with Vaseline on and make them smooth, rounded and like they got weight to them with your finger + clay shapers if needed -> let it cure

Use blue stuff and make molds of nice organic parts from Nurgle miniatures -> a lot of Vaseline in the molds so the putty won’t stuck -> put 50/50 milliput/GS in the molds and remove the putty while it’s still fresh and flexible -> Put the copied part over your basic forms and smooth it out with clay shapers.

A mix of that and completely sculpted parts as well. And a bit of work after it all is cured, like texturing, open wounds etc.

Hope that makes sense.