What are spools?

Some articles on spools, spool:

Tinkertoy - Standard Parts
... In addition to the previously described spools, a standard Tinkertoy set includes Wheels, which are thinner than spools, but larger in diameter ... Like spools, their center holes have a snug fit ... Pulleys, identical to spools, except that the center holes are loose-fitting ...
8 Mm Film - Standard 8
... The film spools actually contain a 16 mm film with twice as many perforations along each edge than normal 16 mm film on its first pass through the camera, the ... When the first pass is complete, the camera is opened and the spools are flipped and swapped (the design of the spool hole ensures that this happens properly) and the same film is then exposed along its other edge ... Common length film spools allowed filming of about 3 minutes to 4.5 minutes at 12, 15, 16 and 18 frames per second ...
Karlsson Spools
... Karlsson Spools AB is a Swedish-based manufacturer of spools for hydraulic valves that are used in hydraulic machinery ... More specifically, the spools are part of directional control valves where the spool slides inside a housing to route hydraulic fluid to mechanical ... The company manufactures valve spools in sizes ranging between 25–400 mm (1”-16”) length and diameters between 5–50 mm (.120”-2”) ...
Devorah Sperber
... is an American installation artist known for creating works out of spools of thread, chenille pipe cleaners and map tacks that act as optical illusions.Some ... For example, her creation of the Mona Lisa using spools of thread is titled After The Mona Lisa 2 ... The spools are hung in long, adjacent columns to create a pointillist, inverted abstraction of a famous painting ...
Magnetic Tape Sound Recording - Commercialization - Standardized Products
... Domestic and portable recorders used seven, five or even three inch reels (or spools) ... Early professional machines used single sided spools but double sided spools soon became popular (particularly for domestic use) ... Tape spools were usually made from transparent plastic but metal spools were also used ...