I've had a very nice set of Hallmark Santa & Reindeer ornament set around since 1992 and have always wanted to do something with them. I found a red MTH 60' flat car that was perfect for the job and went to work.
First, I needed to a way to frame the scene and hold down the snow. Evergreen 1/4" angle was used for the frame rails and cut on a mitre for the corners. The holes for the stakes were carefully measured as they aren't quite uniform and the spacing was laid out on the frame rails and each side labeled so that the holes will match the stake spacing. The stake parts were Evergreen .100 X .100 (2.5mm X 2.5mm) strips. They were cut and glued to the frame rails, then set aside for a day or so to make sure that the bond was dry.
One end piece and one side rail were then glued together with gussets placed inside to add much needed strength to the joint. These again were set aside to set for a day, then the two frame pieces were glued together and gusseted.
I came upon the idea of using magnets to hold down Santa and the Reindeer as I didn't want to do anything to really harm the ornament. To make this "magnetic" thing work, I needed something for the magnets to be attracted to. This came in the form of K&S Tin Coated Steel Sheet #254 .008 X 4 X 10". The sheet wasn't as long as it needed to be, so, I used two pieces and glued them down to the car deck.
Then small rare earth magnets were glued to the bottom of the sleigh runners and to the bottom of the feet of the reindeer that would be touching the ground.
Pieces ready to be assembled.
I used some decorative "snow" cut to length, placed it on the car deck, then installed the frame rail structure in place to hold down the snow. The figures were placed on top from the sleigh forward and small holes were opened up in the snow so that the magnets could touch the bare metal. Everything held just as planned!
MERRY CHRISTMAS Everyone! 
