I make these every year with my students. They are always a great hit and yet, so simple to make. I usually pair it with hot chocolate and The Polar Express movie.
1 roll of lifesavers
1 pack of gum
1 Hershey's kiss
1 caramel square
4 mint candies
Hot glue the roll of lifesavers onto the gum (on top).
Glue the kiss on the "front" of the train and the caramel on the back.
Finish it off with the mint candies as wheels.
Here's another variation I've also tried:
The bottom piece is gum, mints as wheels, a Starburst as the front and a chocolate candy directly behind the Starburst.