Intrinsically card is a good modelling medium.  Easily worked, several different types of adhesives work.  However, for long-term usage as rolling stock with it's attendant stresses & strains, it really needs stabilizing with a good-quality shellac. 

Rolling stock from card is not a new idea, companies like 'Merco' & 'Hambling' (even Peco) were producing the 'When I were a Lad'.

However, I have to ask - what's wrong with plasticard?  Readily available in multiple forms & thicknesses - just needs good bracing to prevent warping over longer runs like coaches AND make sure that interior spaces are vented to prevent long-term damage from solvent fumes that can get trapped inside.

What ever you do - have fun!

Regs

Ian

247 developments do the sides which once you rolled to shape glue to the sides of a shorted Bachmann bulied coach