The cornerstone of the set is a wooden spool roughly two inches in diameter with holes drilled every 45 degrees around the perimeter and one through the center. Unlike the center, the perimeter holes do not go all the way through.
Tinkertoy sticks prior to 1992 were manufactured with a diameter of 1/4 inch. The earlier sets had natural wood sticks, but changed to colored sticks in the late 1950's. From measurement, the orange sticks are 1.25 inches long; yellow, 2.15; blue, 3.35; red, 5.05; green, 7.40; and, purple, 10.85. Spools are 1.35 inches in diameter with holes of 0.30 inch depth.
The sets were introduced to the public through displays in and around Chicago which included model Ferris wheels. Tinkertoys have been used to create surprisingly complex machines, including Danny Hillis's tic-tac-toe-playing computer (now in the collection of the Computer History Museum in Mountain View, California) and a robot at Cornell University in 1998.
Hasbro owns the Tinkertoy brand and currently produces both Tinkertoy Plastic and Tinkertoy Classic (wood) sets and parts.