Greetings, SaraFarrell! I don't see a Trainz version on your timeline, so I can't get specific, but if you search for "christmas" in CM you will find a host of boxcars, hopper cars, and even locos available for download. A few more if you search for "xmas", including Hirochi's high-speed xmas trains. And, AHRian7 has put together some fun Christmas routes and sessions:Routes: Christmas Toy Playground Toys In The Secret Garden at ChristmasSessions: Christmas Toys in the Summer Playground Christmas Toys in the Winter PlaygroundThese routes require a minimum of TRS19, SP5 however. But you can look at some of the rolling stock and get some ideas! Once you have a registered Trainz version showing we may be able to help you with other suggestions.
