Die-cast
Die-cast, as a fandom term, is a metal that was used for parts of early Generation 1 Transformer toys; More correctly, 'Die-Cast' describes the process of pouring molten metal into a mold (die). Die-cast metal was used originally as a production material because due to various oil shortages and embargoes of the late 70's, it was determined to be cheaper to include die-cast metal in toy construction rather than full petroleum-based plastic.
The amount of die-cast in old Transformers toys varies wildly, though it almost never makes up the majority of the toy. In most cases it was used merely for car hoods and occasionally side-panels for the larger toys. In some examples, like Tracks or the Inferno/Grapple mold, only a very small amount of the toy uses die-cast metal. The Generation 1 toys with die-cast metal are among the most breakable of Transformer toys. Examples include Bluestreak's and Jazz's roofs, Mirage's waist, and Swoop's wings and beak.
Die-cast has largely fallen out of favor for Transformers toys for a variety of issues, from durability (both in construction and the paint applied to the metal), shipping costs (due to the extra weight), and mold-detailing issues. Nowadays, die-cast is only used extensively in more "adult-aimed" toy lines, like the now-defunct Japanese Binaltech line, and Hasbro's Titaniums series (which still uses much plastic, including the 3-inch figurines). Parts of the online Transformers fandom complain that current toys are made out of "cheap" plastic instead of the sterner stuff.
Fiction
The legendary Autobot starship known as the Ark was created using die-cast construction. By the era of the Maximals and Predacons, this technique was considered to be a "lost art."
