Computers make everything for humans. Guy gets a model train set made. Next, the guy wants a train kit and the computers refuse, because he would be creating something.
Short story found in a late 70's high school sci-fi text book, I believe.
I think this could well be Rat Race, a short story by Raymond F. Jones, originally published in 1966.
An excellent summary is available from the Mporcious blog. The main points are:
"Rat Race" is set in one of those utopian futures in which robots and computers do all the work so people have nothing to do and find that a life without goals or obstacles is unfulfilling. George Sims-Howton is one such unfulfilled man... He stumbles upon references to model trains, how popular they were among men and boys like 150 years ago, and conceives a desire to have his own elaborate model railroad, a contagious fascination that has soon spread to his friends. By feeding old plans they find into the computer that efficiently runs the world economy, they are soon provided with an abundance of engines, cars, track, scale buildings, etc
This comes to an end however, when he requests a lathe and sheet metal to make his own models - people are forbidden from doing creative work, except for "a narrow elite". The complete story can be read in the April 1966 copy of Analog, available, for example, at the Luminist archive.
It has not been republished widely, but indeed appeared in a school textbook edited by Bernard Hollister entitled You and Science Fiction