Time Estimate: 1.5–3 hours

   Goal: Brainstorm ways to radically reduce your product’s material use through changing its shape.


Step 1: Brainstorm ways to radically reduce your product’s physical material use.

   Time Estimate: 30–60 minutes

Hold a brainstorm session, using the Rules of Brainstorming and whatever collaboration tools you prefer, to generate ideas for reducing your product’s material use as much as possible. Try to get it down to 1/10th the mass it uses today. You might use Factor Ten Engineering Principles to spur your brainstorm.  Be sure to include all the prosaic ideas you have, too. The more ideas the better. But push to radically reinvent your product’s geometry, while still fulfilling your user’s core needs. See if their needs can be met in new ways.

  • Start with the Whole System Map you created for your product, to keep in mind all the components of the system, how they connect to each other, and your product’s role in the larger system.
  • Keep this brainstorm focused on reducing material use in the physical product—not longer life or recycling or reuse, just less material.
  • Try to generate at least 30+ ideas to reduce the amount of material used in different parts of the system, especially parts that have high eco-impacts.
  • Have at least one idea to replace or change every major part of the product.
  • Have at least four ideas that eliminate a component or step in the system.  The more components or steps eliminated by an idea, the more radical the idea. 


Step 2: Narrow down your brainstorm options to 3-4 winning ideas

   Time Estimate: 5–15 minutes

Use dot voting, decision matrices, or whatever tools you desire, to narrow down your brainstorm to just 3–4 winning candidates. In addition to judging each idea by material reduction per functional unit of service, use considerations from your Design Brief to rule out options that don’t meet business criteria such as cost or usability.


Step 3: For each winning idea, sketch and estimate the material reduction of that option.

   Time Estimate: 5–30 minutes

For each of your winning ideas, draw a quick sketch. Then estimate each one’s percent reduction in material use per functional unit of service the product provides. For example, if one idea uses half the material mass, but only lasts half as long because of structural weakness, it does not save any material per functional unit.  Something using half the mass and lasting twice as long would use just 1/4 the material per functional unit, a huge improvement. This is why functional units are important.  Show the math for how you got the estimated percent reduction for each idea.


Step 4: Choose one winning idea and illustrate it.

   Time Estimate: 20–40 minutes

Choose one winning idea (or combination of ideas), based on the percent reduction in materials intensity and your other Design Brief priorities. Create a high-quality image of the winning idea, either by hand or digitally, to clearly convey how the idea is different from the current product, and why it’s a compelling design business-wise.


Step 5: Document your decision and brainstorm.

   Time Estimate: 30–60 minutes

Create a PDF with the winning redesign (or the top few), and the reasons why it is the best option.


Checklist for Lightweighting

Your brainstorm and final document should:

  1. Show the brainstorm on the system map, including showing what new ideas were for what parts of the system, and showing where new ideas eliminated components or steps in the system.
  2. List (or show labeled sketches of) your top 3–4 ideas
  3. List the percent reduction in material use for each of these designs, and show the math.
  4. Show the illustration of the winning design.
  5. Succinctly describe the winning design, either as illustration captions or as a standalone sentence or two.
  6. Briefly describe a convincing business case for the final design choice.