Have you tried this scratchbuilding material?

[marklayton]

Check out this video of the world's largest chocolate train - 112 feet long.  Level of detail is great!  It's on display in the UK.
http://gu.com/p/3cvp7/em

Mark

[Malachi Constant]

Pshaw!  My Mom had them beat by decades!  Used to make me a chocolate train cake for my birthday ... cakes baked in small loaf pans, cut ... "kitbashed!" ... and arranged to make the loco and various cars.  Lifesaver wheels, gum drop bell, licorice "coal" in the tender and so on ... good stuff.

Not as good as Belgian chocolate ... not as realistic as that one you've shown ... but I never got in trouble for eating the chocolate train at home!  I'd be scared to go to that display.  "Do not touch" ... "Do not eat the displays" ... are ya kiddin' me?