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  • Writer's pictureKate

Build What Works

The first three blogs of this series focused completely on forming questions and prioritizing them. The value of devoting time and effort to those exercises becomes clear when you hit the next stage: figuring out exactly what it is you are going to build. “Building What Works” is all about fitting the right object to your question.

If you have read the previous blogs, you should realize that my personal definition of “prototype” is broad. It's not just about parts. The earlier you are in the product design and development journey, the less likely what you build will look anything like a finished product. On the other hand, the closer you get to a final design, the more detailed (and expensive) your builds become. (See my blog exploring this further here).

I've listed my twenty areas of medical device development risk below. The areas that are best understood through research or analytical models, rather than physical objects, have been crossed out. For these remaining categories, what type of object would best answer the unknowns?

Having focused your build to answer a very specific question, you will often find that a complete device prototype is not necessary to answer it. Biocompatibility is all about material properties, and can be tested with just a material sample. When evaluating technical functions, it always easier to debug individual systems before integrating them into the final assembly. Even when getting feedback on a product from different users, designers frequently showcase empty cases or mock-ups. With so many products purchased based on their aesthetics, working electrical or software functions are rarely needed to answer questions about consumer appeal.

Here are ten more object types and the questions they might answer:

  1. Environment How do people act in this space?

  2. Costume How does it feel to carry a pregnancy belly?

  3. Flow Chart Does everyone follow the same steps?

  4. Anatomy Dummy Where can we stick this on a face?

  5. Mechanism How can we lock and unlock these two pieces?

  6. UX Mockup How big do we make the buttons on this menu?

  7. Material Sample What happens if we autoclave this?

  8. Part Sample Which cutting blade works best on bone?

  9. Form Factor How big should this be? How heavy?

  10. Concept Model Would investors find this exciting?

Once you have a general idea of the best type of object to answer your question, take some time to consider how best to implement it. If you are building something to answer a question, you can directly control the form of the answer.

Useful design and engineering data can come in many forms. There’s qualitative (general descriptions, opinions, expression of emotions) and quantitative (numerical data that can be analyzed mathematically). Both types of data can be collected with varying levels of precision (how fine a resolution you have between different answers) and accuracy (did it record the “right” answer). You can measure a user’s arm span with a measuring tape or laser calipers, you can design a survey with five questions or fifty. Whatever you use, make sure the answer data type, precision, and level of accuracy match what you need. Telling design engineers to make a box “not heavy” is an exasperating and all too common occurrence.

Pro Tip: If you're going to design products for babies, keep a "baby" on hand for your design team.

Once you have worked out the form, precision, and accuracy of your answer, you should also consider the number of data points you need to make your answer meaningful. This will quickly lead you to calculating the cost of obtaining said data points. Some tests can be run repeatedly on a single mechanism in a lab, allowing for a high volume of answers relatively quickly. in contrast, collecting direct input from human users can be painstakingly slow.

While most designers will agree that “hands-on” discussions around physical objects produce the most useful data, the challenge of finding and accessing specific individuals in a cost-effective way explains the popularity of virtual surveys and remote interviews. Thoughtful object creation can off-set some of that burden.

In medical devices, it can take many months to observe how physicians perform a particular step in a rare surgery on real patients. Creating a reusable artificial tissue simulator and inviting doctors to a lab would greatly simplify the process. Creating a simulator that could be packed into a suitcase and taken to a medical convention would improve the data collection process even further. Adding pressure sensors, a motion tracking camera and a continuous data logger can generate enough data to create a design optimization algorithm to drive the entire design of a new surgical tool. Alternatively, two chopsticks, a bowl of spaghetti and a cell phone camera can work in a pinch. Being able to pull valuable insights out of both approaches is all about the next post topic: Flexibility.


What object would answer your question most effectively? It may be only a single part or sub-assembly of your final product. It may not be part of your product at all, but replicate some key part of the product’s use context. How can you create this object in a way that meets your requirements for precision, accuracy, ease of use and cost?

About this Series

This is the 4th installment of a ten-part series on prototyping strategy. This is not about how to pick a 3D printer or get a nice finish on your painted parts, but a deeper reflective dive into the why and how we go about building the things that help us design better products. The points I focus on are not just to better align your project with some design "ideal", they are a way to manage the very real problem of every entrepreneur or program manager - build it fast, build it right, with as few resources as possible.

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