Prototypes are generally a mix of digital and analog production. In many cases, the actual object may not exist and the project involves taking a drawing or concept and designing and applying graphics to a realistic material look to an image. 
Other times, there may be a physical prototype developed and the direction is to develop branding, packaging or other graphics to a physical sample. Often this sample is not created from the actual material so it is necessary to print fields that represent the product or liquid filling the vessel. Printing in small quantities on a variety of substrates and surfaces is more technical than it might seem.
These projects are largely exploratory and often are never produced en masse. They do require a great deal of experimentation, trial and error, and most importantly, perseverance. The projects usually involve careful measurement and die line creation, graphic design for package development, printing, mock up assembly and photography and digital image creation and retouching. 
Graphics Design: Roger Stewart
Printing/Proofing: Patterson Rush
Mock Up Artists: Jill Wiscombe and Bill Roper
Creative Management/Direction: Gabe Hamrick
Packaging Mock Ups
In the packaging world mock ups have an incredibly diverse set of uses. When manufacturers are changing a design on packaging or want to test a new material or pack configuration, they will commission mock-ups to see how a product looks on shelf or fits a new need. The Coca-Cola mock-up at the bottom of this page was used to test how the can product would be received in a shrink film 18 pack configuration prior to commercialization. 

If a pack design is nearing finalization, the colors, finishes and design will be tested in a mock up, such as the Keurig Dukale's Blend mock up. This package has a mixture of gloss and matte finishes to give a premium look to the product and the mock-up helped the team determine the best way to use these materials to highlight their brand and key information on the packaging prior to full production. 
Mock-ups are also used for hero photography. See the Fanta Zero can below and note that all legal text has been removed to emphasize brand and flavor queues. 
These projects require much of the same production planning that traditional commercialization requires, but at a smaller scale. The projects can be quite complex with many steps required to create a "one–off" mock-up that achieves the desired look. 
Graphics Production: Roger Stewart, Gabe Hamrick
Printing/Proofing: Patterson Rush
Mock Up Artists: Jill Wiscombe and Bill Roper
Photography and Retouching: Roger Stewart
Creative Management/Direction: Gabe Hamrick