Why?
When I talk about unsatisfactory models it is because they are unsatisfactory to me, and perhaps only to me, for a specific reason: they look like the real thing, they seem to act like the real thing, but on closer inspection there are irritating oversimplifications. I am talking about working or illustrative models. I discuss a few cases in greater detail, and in each case my reflection was:
if the real thing worked like the model, it would not perform properly.
In other words, a real object based on the Lego model would be a failure. These models could not be used to explain their principles of operation.
A Boxer Motor
A boxer motor is a piston engine with opposing pistons. The best known example is the engine of the Volkswagen Beetle: a four cylinder, air-cooled boxer motor. Most light aircraft are also powered by this type of engine.
I built two different boxer motors.
The Grand Carousel
A carousel is a merry-go-round amusement ride for children and adults. Classically it has rows of wooden horses that go up and down as the platform rotates.
Lego did produce a large set for a carousel, with horses that move up and down.
Starting from this set I built a more accurate model of a carousel.