A good designer will decide early on which materials and methods of manufacture to use. This is because how things are made, and what they are made from, has a big impact on the shape and form of the product. Today's designers often use 'smart materials' in their products. These are materials that can respond to differences in temperature and light. A good example is the lenses of some sunglasses that change colour depending on the level of sunlight.

Design and manufacture are also influenced by the number of products which are going to be made. These tend to fall into one of four categories:

• one off – where just one item is made, often for a specific client, for example, designer clothing
  
  
• batch production – the manufacture of between 2–2000 items, for example, artists' prints
  
  
• mass production – when thousands or millions of items are made, for example, cars
  
  
• continual flow – non-stop production, twenty-four hours a day, for example, crisp manufacture

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Whether it's a one-off or a mass-produced item, a good designer always tries to find ways to cut down on waste and increase manufacturing efficiency as much as possible. This is where quality control comes in. This is where the product is continually compared to the original plan to make sure it meets the required standards.

Computers are being used more and more in design and manufacturing. Computer-aided design (CAD) allows designers to see their ideas in three dimensions on the screen, and also to develop, adapt and edit their designs with ease. Computer-aided manufacturing systems (CAM) feed the information contained in the CAD directly to machines which can produce the item very quickly and accurately. This makes it easier for designers, production engineers, manufacturers and marketing departments to work together more easily because they can all have access to the design information. This dramatically reduces the time it takes for a new product to reach the market place and also saves money in the development of ideas that, for technical reasons, are not possible to later manufacture.

The designers of the Jumbo Pack have carefully considered the likely method of manufacture of their pack from an early stage so helping to ensure that the container can be produced economically.

Satisfied with the CAD design, they decided to go one stage further and mock up a prototype in polystyrene.