Here's some great nuts-and-bolts industrial design by veteran Dutch consultancy Flex. The firm was contacted by PostNL, Holland's mail service, and asked to apply their ergonomic expertise to make things easier for employees working the sorting line.

"Mail consists mainly of paper and paper is heavy," the firm explains. "When processing the required volume of mail for the sorting machines, the sheer weight of the processed amount would lead to strains on the operators that would exceed legal and desirable limits."

Flex studied the problem of moving heavy mail loads off of and onto sorting machines, as well as carting stacks of the stuff across the facility. They concluded that a specially designed ergonomic cart, one that allowed workers to slide mail onto it with little effort, would fit the bill. They then set about executing their "Fail quickly and cheaply" prototyping process:

"Throughout the development process we made numerous wooden prototypes that taught us a lot about the workings and usability of the aid. Going through a number of iterations this way, we finally landed on the optimized design," which they named the ISM (Intermediate Storage Means) Cart.

"Reliability and durability were pivotal demands for PostNL. The ISM is packed with smart solutions to take care of this. By making clever use of gravity (the most reliable force of all), we make sure that the handles and levers always work and the red mail-tray sits stable on the frame."

"An innovative addition to the caster wheels ensures the ISM effortlessly rides over bumps and thresholds. Karts link together cleverly and can be moved en masse. Because of the specially designed frame, a forklift can transport a stack of karts in one go. Once emptied, the karts nest together in an extremely compact configuration."

Flex set up a small-batch production run of 300 units for testing in sorting centers, and quickly learned that they'd knocked it out of the park. "What amazed us," says industrial designer Ronald Lewerissa, "was that already during the pilot phase the ISM was almost part of the day to day routine of the PostNL operators."

A further 5,000 units were commissioned, and the ISM then became an indispensable tool for PostNL. Here's how the unusual-looking cart helps workers execute three crucial tasks:

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