Slide-mold?

Molds separate into at least two halves (called the core and the cavity) to permit the part to be extracted. In general the shape of a part must not cause it to be locked into the mold. For example, sides of objects typically cannot be parallel with the direction of draw (the direction in which the core and cavity separate from each other). They are angled slightly (draft), and examination of most plastic household objects will reveal this. Parts that are "bucket-like" tend to shrink onto the core while cooling, and after the cavity is pulled away. Pins are the most popular method of removal from the core, but air ejection, and stripper plates can also be used depending on the application. Most ejection plates are found on the moving half of the tool, but they can be placed on the fixed half.

More complex parts are formed using more complex molds, which may have movable sections called slides which are inserted into the mold to form features that cannot be formed using only a core and a cavity. Slides are then withdrawn to allow the part to be released. Some molds allow previously molded parts to be reinserted to allow a new plastic layer to form around the first part. This is often referred to as overmolding. This system can allow for production of one-piece tires and wheels.