Halfords is a major bicycle and car parts retailer with long history in the market.

Explanation

3D-printed parts can replace traditional metal parts. They are also more easily customised to fit customer's needs. This technology is an example of threat of substitute in Porter's Five Forces model.

Substitute goods or services that can be used in place of a company's products or services pose a threat. Companies that produce goods or services for which there are no close substitutes will have more power to increase prices and lock in favorable terms. When close substitutes are available, customers will have the option to forgo buying a company's product, and a company's power can be weakened.