Steam locomotives come in all shapes and sizes, this is because their intended tasks require varying traction...
I would not recommend sitting on one, but otherwise they are very good and sturdy. Most card kits are made of thick card and the design will create several layers of card, reinforcing the structure.
They are easy to make simply by following the instructions.
Card kits have a very realistic finish, there is so need for painting, saving you time.
There is a wide choice of buildings in N gauge and OO scale. When made well, they take on an appearance which is better than some of the plastic kits available.