Just a quick aside, but the Scale 75 metallic paints are superb! I’ve painted an axe head relatively quickly using them and they work really well!
No streaking, and no real build up of metallic pigment as you can sometimes get. It almost seems to self-level as it dries. They are also really reflective.
Very cool!
Jolly Bodgers 
Going off topic here so this is not intended to create discussion but I don’t understand NMM when it is so much easier to use metallics. Probably because I struggle getting an effective NMM finish.
The choice between metallics and non-metallics in my mind is purely a matter of taste. There is a certain amount of control you can get by painting in NMM in terms of positioning of light etc, but really it is a style thing.