A 1950s Lionel train advertisement shows a father, mother, little girl and boy peering into a window display featuring a model train going through a city, over a bridge and into the mountains. The father appears to be the most interested -- head cocked, hand on his chin, ready to help his child build the toy train set. An adjacent Lionel Train advertisement shows a father sitting on the ground assembling a train set, while his son sits in the background frowning. California State Railroad Museum's "Some Assembly Required" exhibit, which opened today, featured a somewhat similar scene. Many families were in the museum, but the historical toy exhibit seemed to strike the strongest chord wi