decorating a sponge train cake

Oreo cookies make quite good wheels.

Thanks for the replies; it's not easy if you are [like me] a novice about such things, however, I made the cake today and amazingly it did come out of the cake mould more or less ok [ooops!]So, I will ice and decorate it soon, marshmallows and sweets will I hope, make it look better.

I dont know about the gluten free bit, but how about using firemans laces red and blacklaces, matchmakers, liqurice allsorts, or depending on the size you could use orio biscuits for wheels, black liqurice pieces for coal, thats all I can tthink of now but will set my brain to steep.

Oh heavens! It does sound as if you are going to have your work cut out with the gluten free bit! I was going to suggest the wagon wheel chocolate biscuit things that you could add lines of icing to, to suggest spokes, but that won't work, will it?