Thermoforming is a manufacturing process where a plastic sheet is heated to a pliable forming temperature, formed to a specific shape in a mold, and trimmed to create a usable product. The sheet, or "film" when referring to thinner gauges and certain material types, is heated in an oven to a high-enough temperature that permits it to be stretched into or onto a mold and cooled to a finished shape. Its simplified version is vacuum forming.

In its simplest form, a small tabletop or lab size machine can be used to heat small cut sections of plastic sheet and stretch it over a mold using vacuum. This method is often used for sample and prototype parts. In complex and high-volume applications, very large production machines are utilized to heat and form the plastic sheet and trim the formed parts from the sheet in a continuous high-speed process, and can produce many thousands of finished parts per hour depending on the machine and mold size and the size of the parts being formed. Thermoforming differs from injection molding, blow molding, rotational molding and other forms of processing plastics.

Thin-gauge thermoforming is primarily the manufacture of disposable cups, containers, lids, trays, blisters, clamshells, and other products for the food, medical, and general retail industries. Thick-gauge thermoforming includes parts as diverse as vehicle door and dash panels, refrigerator liners, utility vehicle beds, and plastic pallets. In the most common method of high-volume, continuous thermoforming of thin-gauge products, plastic sheet is fed from a roll or from an extruder into a set of indexing chains that incorporate pins, or spikes, that pierce the sheet and transport it through an oven for heating to forming temperature.

The heated sheet then indexes into a form station where a mating mold and pressure-box close on the sheet, with vacuum then applied to remove trapped air and to pull the material into or onto the mold along with pressurized air to form the plastic to the detailed shape of the mold. (Plug-assists are typically used in addition to vacuum in the case of taller, deeper-draw formed parts in order to provide the needed material distribution and thicknesses in the finished parts.) After a short form cycle, a burst of reverse air pressure is actuated from the vacuum side of the mold as the form tooling opens, commonly referred to as air-eject, to break the vacuum and assist the formed parts off of, or out of, the mold. A stripper plate may also be utilized on the mold as it opens for ejection of more detailed parts or those with negative-draft, undercut areas. The sheet containing the formed parts then indexes into a trim station on the same machine, where a die cuts the parts from the remaining sheet web, or indexes into a separate trim press where the formed parts are trimmed. The sheet web remaining after the formed parts are trimmed is typically wound onto a take-up reel or fed into an inline granulator for recycling. Most thermoforming companies recycle their scrap and waste plastic, either by compressing in a baling machine or by feeding into a granulator (grinder) and producing ground flake, for sale to reprocessing companies or re-use in their own facility. Frequently, scrap and waste plastic from the thermoforming process is converted back into extruded sheet for forming again.

Die cutting is the process of using a die to shear webs of low-strength materials, such as rubber, fiber, foil, cloth, paper, corrugated fiberboard, paperboard, plastics, pressure-sensitive adhesive tapes, foam and sheet metal. In the metalworking and leather industries, the process is known as clicking and the machine may be referred to as a clicking machine. When a dinking die or dinking machine is used, the process is known as dinking. Commonly produced items using this process include gaskets,[4] labels, corrugated boxes, and envelopes.

Die cutting started as a process of cutting leather for the shoe industry in the mid-19th century. It is now sophisticated enough to cut through just one layer of a laminate, so it is now used on labels, stamps, and other stickers; this type of die cutting is known as kiss cutting. Die cutting can be done on either flatbed or rotary presses. Rotary die cutting is often done inline with printing. The primary difference between rotary die cutting and flatbed die cutting is that the flatbed is not as fast but the tools are cheaper. This process lends itself to smaller production runs where it is not as easy to absorb the added cost of a rotary die.

Rotary die cutting is die cutting using a cylindrical die on a rotary press. A long sheet or web of material will be fed through the press in to an area known as a "station" which holds a rotary tool that will cut out shapes, make perforations or creases, or even cut the sheet or web into smaller parts. A series of gears will force the die to rotate at the same speed as the rest of the press, ensuring that any cuts the die makes line up with the printing on the material. The machines used for this process can incorporate multiple "stations" that die cut a particular shape in the material. In each of these stations lie one or more of these geared tools or printing cylinders, and some machines use automatic eye registration to make sure the cuts and / or printing are lined up with one another when higher tolerances are required. Dies used in rotary die cutting are either solid engraved dies, adjustable dies, or magnetic plate tooling.

Engraved dies have a much higher tolerance and are machined out of a solid steel bar normally made out of tool steel. Adjustable dies have removable blades that can be easily replaced with other blades, either due to wear or to cut a different material, while magnetic plate tooling has a cylinder that has magnets placed in it, and an engraved metal plate is attached or wrapped around the base cylinder holding onto it by the force of the magnets.

Vacuum forming is a simplified version of thermoforming, whereby a sheet of plastic is heated to a forming temperature, stretched onto a single-surface mold, and forced against the mold by a vacuum is formed into permanent objects such as turnpike signs and protective covers. Normally draft angles are present in the design of the mold (a recommended minimum of 3°) to ease removal of the formed plastic part from the mold. Relatively deep parts can be formed if the formable sheet is mechanically or pneumatically stretched prior to bringing it into contact with the mold surface and applying vacuum.

Suitable materials for use in vacuum forming are conventionally thermoplastics. The most common and easiest to use thermoplastic is high impact polystyrene sheeting (HIPS). This is molded around a wood, structural foam or cast or machined aluminium mold, and can form to almost any shape. Vacuum forming is also appropriate for transparent materials such as acrylic, which are widely used in applications for aerospace such as passenger cabin window canopies for military fixed wing aircraft and compartments for rotary wing aircraft. Vacuum forming is often used in low-level technology classes for an easy way to mold.