This story is part three of MakerBot's series of design studies, exploring iterative design and the relationship between designers and their tools.

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So far we've explored form development with the bike saddle and reverse engineering with the drone rebuild—now it's time to push into something a bit more futuristic.

Footwear design is a deceptively complex category that has much more in common with automotive design than it does with most fashion disciplines. There's ergonomics, mechanics, loads of different material properties, and on top of all of that—aesthetics. 

Not being trained a footwear designer myself, it's an inspiring albeit daunting path, but that impending challenge is a good feeling and there's no better way to learn than by doing.

1. Select Realistic Shoe Goals

I began this exercise by splitting the shoe geometry into its two components: the sole and the body. Each of these parts have their own anatomies with richly interrelated components, but I'm a shoe rookie and stand almost no chance at getting a shoe right on my first try. In the diagram below you can see how I started to define different planes on the body, but quickly got overwhelmed. Kudos to all of my footwear design counterparts that make this look so easy.

Instead of focusing on designing a game-changing shoe, I'm going to focus on just the sole to test parametric design tools and study exotic geometries.

You've probably seen the cross section of a running shoe sole; some of them are even transparent. They have a patterned honeycomb or lattice geometry that's optimized for high impact resistance and low weight. This is a great opportunity to explore different parametric lattices that can be easily iterated on to change specific performance needs.

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2. Create Parametric Lattices

This is Grasshopper, one of my favorite CAD tools. It's a graphical algorithm editor that runs in Rhino and allows the user to create geometries with dynamic parameters in an intuitive drag-and-drop space.

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Parametric tools are incredibly powerful when paired with a 3D printer. Once I have a geometry for different lattices defined, I can explore tons of different versions of the pattern in a short period. I export a sole with a wide pattern, a tightly grouped pattern, a thick and a thin pattern. With a single bounding geometry in place, there's no limit to the number of variations I can create—the real constraint is how many I can print and evaluate in a short period.

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3. Prepare the Soles for 3D Printing

There are a bunch of different 3D printing technologies out there. Each with its own set of advantages and disadvantages, materials, tolerances, speeds, etc. Adidas rolled out a 3D printed shoe a while ago which may even validate using particular 3D printing technologies for cost-effective, short run manufacturing.

For early studies, we don't need the springy high-tech plastics that will make up the final shoe, we just need speed, reliability, and accuracy. In this case, FDM or Fused Deposition Modeling is the ideal platform (and conveniently the least expensive), and my FDM printer, the MakerBot Replicator+, is a true workhorse for rapid prototyping.

I drag the first batch of iterations into MakerBot Print which will gives me a slicing preview to confirm the STLs are imported correctly. Once imported, I adjust the print settings and start with a sturdy .4mm layer height for the first iterations. Using wider layers at first means there are less possible failure points across the sole, but also a lower resolution or surface quality. Once I confirm .4mm works, I then test .3mm and eventually stick with .2mm—a layer height that offers the right balance between surface quality and structural integrity for this particular print.

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4. Explore Applications for Lattices

The parametric geometries I set up could be modified to serve multiple purposes. After printing a variety of soles, I considered how a gradient that transitions from a tightly grouped lattice to a more loosely grouped one could distribute and direct force away from high impact zones. The more I tinkered with the parameters, the more the project felt like a previous concept I explored that went on to win a Red Dot Design Award, pictured below.

Parametric models are becoming increasingly important as the foundation for generative design techniques that incorporate huge data sets for things like material properties and force simulations. Imagine outlining the rough geometry for a sole and setting goals for heat or impact distribution, then sitting back while AI exhaustively explores every permutation of the design before selecting the best one for you. This is the very exciting (and very real) future of product design and additive manufacturing.

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5. Revise and Reprint

With five unique variations, I decided to focus on the one that gave the best balance of aesthetics and functionality. There's some stylized and functional lattice at the ball and heel of the sole, localized to the most relevant areas, but not so much that it begins to add visual noise or interfere with the overall shape and look of the shoe.

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6. Print the Final sole and Experiment with Materials

Having MakerBot's Experimental Extruder handy, I was also able to prototype the shoe's body and sole in some different flexible plastics, adding an extra layer to my experience. I grabbed some community tested material profiles from the Thingiverse group for MakerBot Labs, then imported them into MakerBot Print and fired up a sole with a popular flexible material called NinjaFlex.

This exercise was a great way to experiment with parametric design in an unrestrictive way. Ultimately, these complex and uneven geometries prove to be a great source for concepts that can only be created with a 3D printer, helping designers push the boundaries of what products and technologies are possible in footwear design and other fields.

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MakerBot, the Brooklyn-based 3D printing company, pioneered the first connected desktop 3D printers and operates Thingiverse, the world's largest 3D printing community and file library.