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  • Writer's pictureKate

Build in Flexibility

Effective prototyping requires a tightrope walk between the left and right sides of the brain. As much as I lecture on planning and structure in one’s approach, there must be room for creativity and serendipity. It is how you rapidly pivot and maintain forward momentum when your original approach fails. In building physical objects, flexibility is both a state of mind, and a very real engineering strategy.

When I was a young teen, I was obsessed with dollhouse miniatures. Lacking the money to buy them directly or the skills and tools to craft from raw materials, I took to wandering through places with what I thought of as my “miniature eye”. Creamer capsules were the perfect size for a 1/12th scale waste basket. The finely printed patterns inside security envelopes were repurposed into various small scale paper projects. Beads were doorknobs and the ubiquitous white plastic pizza topper were living room tables.

This intentional “forgetting” of the actual purpose of objects is a wonderful tool for seeking out materials and parts for prototyping. Whether walking through a hardware store, a toy store, or even the dark corners of my own garage, my first impulse to resourcing a new part is to attempt to “find” it in the wild, rather than build it from scratch. As I’ve written earlier, efficient prototyping is no place for the ego of hand craftsmanship. Precision machining or welding prototypes all by yourself does not necessarily improve the quality of the answer they give. Found objects, in fact, can provide surface finishes and joining methods that are near impossible to achieve with small scale production technologies.

When I work with medical device innovators, I encourage them to start a collection of finished medical products to hack and modify. This is not for reverse engineering purposes, but because procuring existing devices is often the easiest way to obtain precision ground cutting edges, biocompatible plastic tubing, and skin safe adhesives. I also recommend prowling through cooking and food handling products, since they frequently follow similar material and manufacturing controls. Regardless of what industry you work in, it is extremely useful to build your own collection of “raw materials” from products in similar or adjacent industries.

If you find yourself struggling with the imaginative play aspect of this technique, it can help to develop your own “prototyping eye” with practice. In formal psychology terms, the cognitive bias that limits you to using an object only in the way it is traditionally used is called “functional fixedness.” Like any cognitive bias, you can reduce it through training.

Grab a random object from your desk, bathroom, purse or other source of clutter. Place it on a clear surface and imagine de-focusing your gaze. However, instead of doing this physically with your eyes, imaging doing it mentally with your knowledge of the object in front of you. Once the knowledge of what the thing is and how you use it has blurred out, start thinking about what else it could be.

Maybe there was a spoon on your desk from your morning coffee.

There is now no spoon.

There is a polished concave (and convex) surface. There is a fixed weight that is just right for an object to be held comfortably in the hand. There is an electrical and thermal conductor. There is a handle. There is a thin, stiff edge. There is a source of corrosion resistant, food grade metal. Bang it against the desk and you have a noise maker. Hold it over a flame and you have a teeny tiny melting pot.

I encourage my students to perform these mental calisthenics regularly, but I also teach them the more formal approach of intentionally building flexibility into your prototypes. Efficient prototyping is not the creation of a series of stand-alone, individually resourced and assembled units. While every object build should focus on one specific question at a time, there is nothing that prevents you from adapting, reusing, disassembling, re-applying, borrowing from and re-arranging your older builds into new ones. One of my favorite chapters of Adam Savage’s Book “Every Tool is a Hammer” has him waxing poetic over screws. Unlike joining with glue or nails, what is screwed together can be unscrewed. Purposely choosing reversible joining methods, adding a little more material to make parts last longer, and avoiding excessively specific features that are not critical to answering your current question are all favors you do for your future self (See Chapter 13 of Adam’s Book).

There is an apocryphal story of the early days of usability design concerned the placement of cockpit flight instruments. A series of pilots were shown a blank mockup of a dashboard, then handed a bucket of dials, knobs, and switches to place as they saw fit. Instead of showing pilots a fixed design, design researchers gave them a flexible prototype that could be modified, photographed, and then reused to document the feedback of dozens of pilots. I used this same approach in a catheter handle design project that required the feedback of a team of interventionalists in another part of the state. Rather than send them a dozen handles, I mailed then a block wrapped in Velcro, and a dozen buttons, knobs, and switches. The doctors debated among themselves (in my blissful absence) and sent me the result: a picture of the base form with the exact knob and button placement they wanted. I did not even start up my CAD software until I had that picture in hand.

A final word on Building Flexibly: having the resources on hand to pivot and move quickly, and to not get lost, takes some discipline. Keeping piles of building materials around is useless if it is too messy to find what you need. I probably spent days picking up, re-boxing and re-spooling prototyping materials in the scrap rack at my old design firm. However, when I had to drop everything and grab materials for a quick test, I had what I needed immediately. I built a reputation of speedy work and making things happen, just because I knew where stuff was. I was also able to constantly reuse builds because of my documentation. I photographed every build and annotated them extensively in my workbook. No matter how many times a fixture or case was re-cycled, I could retrace my path backwards and lay out what was done and learned at each step.


If you could only build your next prototypes with found objects and a screwdriver, what would you use? When was the last time you just “browsed” through a hardware, toy, craft or household supply store for more than ten minutes? Next time you find yourself in one: wander a few aisles developing your “prototyping eye”, wear down your functional fixedness, and see what new opportunities you find.

About this Series

This is the 5th 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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