Anybody tried using artists flat coat. Comes in big cans and much cheaper than "model" variants. It is used to dull paintings after they are painted.

I've considered trying it. But I wonder if it might not be too thick, or heavy, for fine detail. I hope someone here has used it.

Yes...I've tried it...and cfbush...you're right....it's not fine enough for figures....but might be OK for armour or used in dioramas and such.