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Sandals are among the oldest forms of footwear, historically shaped by geography, material availability, and cultural utility. Once synonymous with simplicity, they have become fertile ground for experimentation – blending tradition, technology, and unapologetic innovation. From ergonomic reinventions to high-concept prototypes, today’s sandals are no longer just summer staples, but rather design statements.

The Iguaneye Jungle from the Portuguese footwear company Iguaneye, whose designs are often grounded in both anthropological reference and material science, draws conceptual inspiration from Amazonian tribes who once coated their feet in natural latex rubber to protect them from the forest floor. Rather than merely mimicking this gesture, Iguaneye translates it into a contemporary ergonomic object that aims to replicate the sensation of a second skin.

At the core of the design is a two-part rubber sole that conforms to the foot’s anatomy. One of its most subtle yet thoughtful details is the repositioning of the toe separator, which is placed slightly forward to avoid the irritation often associated with traditional flip-flop designs. The result is a sandal intended to move fluidly with the foot, responding to natural biomechanics without interrupting them.

To achieve this, the design team developed a digital 3D model using Rhinoceros 3D software, working in collaboration with the prototyping firm Inpact. A series of test versions were produced using selective laser sintering (SLS) technology, allowing for the rapid iteration of complex geometries. The chosen materials (Duraform Flex and Duraform TPU) strike a balance between elasticity and structural integrity, making them suitable for a wearable object that needs to bend, grip, and endure.

If the Iguaneye Jungle explores the future of ergonomic design, Ellie Kim’s Swapz takes a closer look at sustainability through modularity. Most slippers, no matter how well-loved or comfortable, are destined for a short life. A broken strap or stained upper is usually all it takes to send them to the landfill, even when the soles remain structurally sound. Kim, an industrial designer based in California, observed this common pattern and responded with a concept that challenges the throwaway model at its core.

Swapz is built on a simple but clever idea: what if the upper part of a slipper could be swapped out just as easily as a phone case? At the heart of the design is a custom rail system integrated into the slipper’s sole. The straps, which come in a variety of materials and colors, slide smoothly into this rail and lock into place with a click. No tools, adhesives, or fasteners are required. The result is an intuitive, tactile interaction that feels more like snapping together a toy than maintaining a piece of footwear.

This modular system opens up an unexpected world of customization. Users can change their slipper straps to suit the season, their mood, or even a particular outfit. Kim has also envisioned a community aspect, where individuals could design and share their own strap creations. This transforms the product from a static object into a platform for expression and reuse.

What stands out about Swapz is how naturally it incorporates sustainable thinking into its design. Rather than moralizing about consumption, it simply makes keeping and adapting your slippers more appealing than discarding them. The modular approach extends the lifespan of the product without sacrificing aesthetics or comfort.

While modularity can help reduce waste in the consumer market, another design story takes the idea of adaptability further by addressing a more urgent need. In 2007, during a visit to Kenya, Kenton Lee noticed a young girl wearing shoes far too small for her feet. That moment became the catalyst for The Shoe That Grows — a sandal designed to expand in size as a child’s foot grows. Lee would go on to found Because International, a nonprofit built around the principle of improving lives through better products, starting with footwear.

Children in low-income communities often face a difficult dilemma: they grow quickly and must continue wearing footwear that no longer fits, or worse, go without any shoes at all. Both options come with consequences — discomfort, lack of mobility, and exposure to health risks such as soil-transmitted diseases and injury.

The Shoe That Grows offers a solution by introducing adjustability as its core design feature. The sandal can expand across five sizes through a system of buckles and expandable panels, functioning in much the same way a belt does. Constructed from durable, locally sourced materials such as compressed rubber soles, leather uppers, and metal hardware, the shoe is engineered for both comfort and long-term use, even under demanding conditions. It is designed not just to endure but to adapt, supporting children through years of growth rather than months of wear.

Unlike many other innovations in the footwear space, this project places humanitarian design at the forefront. It highlights how a small but meaningful intervention can generate lasting impact. While the shoe itself is modest in form, its implications are expansive, offering a blueprint for how thoughtful, resource-conscious design can intersect with global challenges in a tangible, scalable way.