The other day I had the chance to inspect in detail a 'O' DMU. As I turned it over I was surprised to find the chassis was a piece of wood !
Don't get me wrong, it was a beautiful crafted and detailed loco, but the basic concept was a wood board fitted with the running gear and the body shell placed on top.
I know some of these ready to run models cost =A3500 to =A32000 plus, although I have seen for example a Heljan Class 35 for about =A3270, and the kits from about =A3400 upwards, it just surprised me they would simply use a piece of wood.
Still if it works then it works :-)
Chris