Small parts cilinder based on DIN EN 71-1.
More infromation:
https://tukes.fi/en/products-and-services/toys/small-parts-in-toys-and-other-products-for-children
A small part is any component that completely fits inside the cylinder used to measure small parts. The cylinder is 57.1 mm high and its diameter is 31.7 mm. The cylinder is the size of the throat of an average 3-year-old.
The author marked this model as their own original creation.