Novelty item

The term also applies to practical items with fanciful or nonfunctional additions, such as novelty aprons, slippers, or toilet paper.

The French mathematician and astronomer Pierre Hérigone (1580–1643) describes a novelty item that was a camera obscura in the form of a goblet.

One of the more popular novelty items in recent history was the singing Big Mouth Billy Bass, manufactured by Gemmy Industries.

According to The New York Times, Elizabeth II displayed a Big Mouth Billy Bass on the grand piano of Balmoral Castle.

[1] Novelty items based on mathematical objects, such as Klein bottles and Penrose triangles, have been manufactured.

Pet rocks with googly eyes , a novelty item popularized during the 1970s
Humorous novelty signs
A 3D printed Penrose triangle