All the imported brass engines and cars we have in the US and Canada start life as "etched brass" kits since etching the parts is the first step in constructing them.
Someone mentioned on one of the podcasts about how "the best etched metal parts seem to come from England" - and they didn't know why. The answer is simple - etched kits like the locomotive shown in the original post have been commonplace in Europe for decades.
I have one at home (for an OO old time 4-4-0 - that's not much bigger than an N scale steamer!!) and the stacks of etched brass frets in the box are truly amazing. Everything is folded and then layers of frets are laid one on top of the other to build up the parts.
Although the N scale and OO locomotives are neat, the 7mm (O scale to us) engines are truly stunning models when built up.
If you want to build etched brass locomotive (or car kits) I'd highly recommend the two books my friend Iain Rice - who builds these things for hire - wrote for Wild Swan -
http://www.titfield.co.uk/WSM_LOCO.htm#545 - Etched Locomotive Construction, and Locomotive Kit Chassis Construction.
Although focused on P4, the techniques apply to building these kits in any scale.
Marty