Later, the students went back with a few more, and within a few days the young lady had bought them all for a high price.
The next instalment, and you may have seen this coming, is that the students went in with a box containing dozens of these things, which the shop owner purchased outright.
They remained there for several years!
If you are the owner (shopkeeper) then you are expected to be able to explain the hows and whys of the art contraptions as a respected creator/dealer.
If you are simply a consigner then the buyer is left to
their imagination.