Am going to be painting my own ones of those shortly. .. would love a painting tutorial!!
I was planning on documenting my progress through a set of Mr Handys today but it's been such a busy day and I've been doing several things to keep on top of work so those plans have fallen by the wayside.
I can give you my metals recipe though.
Base coat mix of VMA Steel, VMC USA Olive Drab and a little black. For the first layer of highlight just add some more Steel to the base mix. You can layer that on pretty quickly, you could even overbrush it. Next highlight layer, pretty much pure Steel, again quickly layered. Neatness doesn't matter too much at this point as some washes will pick out the detail. Let the paint dry fully before doing the washes.
Washes: First off a mix of undiluted GW Nuln Oil and Agrax Earthshade (about 3 parts black to one part brown). Cover everything, maybe clean up any heavy pooling, especially on flat areas. Let it dry then hit it again with the same wash but add a little water to thin it this time.
When that's dry give it a paint wash, a mix of VGC Charred Brown and VGC Imperial Blue. The mix wants to be a little more brown than blue. Thin it with water but it should still be quite heavy. Use a clean wet brush to tidy up any nasty pooling or if it looks a bit heavy in places. You can focus the wash more heavily in some places if you want more grime.
When that's dry I use another paint wash, this time VGC Parasite Brown. This is for rusting. You can thin it right down and wash the whole model to add a light rust everywhere or you can keep it quite heavy and focus it in key areas. You can build up heavier colour with more washes if you like.
Final job is to pick out all the edges, bolts, panel lines, whatever with Steel. Use broken lines of Steel to give a chipped look.
It's quite quick but there is a lot of waiting around for washes to dry.