Coupling and Timber dimensions

Hey guys, my woodshop teacher wants me to make a toy train out of timber and I need to include dimensions to make sure that type of timber is the right one. I've looked all over the net and I can't find timber dimensions!

Also, I need coupling to stick the carriages together but I can't find any either! All I got were magnetic ones from thomas the tank engine toys. Do you know other styles? Can someone please help?

I know this is definitely not poetry stuff but, yeah. Please reply!

Try this:
http://www.mistupid.com/homeimpr/lumber.htm

You might try model train shops for the couplers.

Sounds like an interesting project. Good luck with it.