sliced open and rebuilt, discarded tennis balls become wearable shoes

tennis balls sliced into shoe components

With its springy rubber shell and a grippy curving surface, a used tennis ball already contains much of what a shoe needs. For SLICE, designer Soroosh Riazi Isfahani begins with those existing qualities, cutting discarded balls into repeatable components that can be assembled around the foot. The fluorescent yellow skin remains instantly recognizable, complete with white seams, printed logos, and patches worn down through play.

Custom 3D-printed guides hold each ball in place while a blade follows a set path across its surface. The cuts release curved bands and deeper cup-like sections, turning the pressurized sphere into a small kit of footwear parts. Wider pieces wrap across the forefoot, while narrower strips follow the sides. Black stitching and cord connect the sections around an inner structure to create a shoe whose construction remains visible from every angle.

images © Soroosh Riazi Isfahani

the sphere becomes a construction system

Designer Soroosh Riazi Isfahani first approached the material through a familiar recycling process, shredding old tennis balls and mixing the particles with natural rubber to form a shoe’s outsole. That method produced a usable compound, though it erased the qualities that made the tennis ball useful in the first place. The curved form disappeared, and so did the layered bond between the rubber core and its fuzzy exterior.

Slicing offered a more direct route. Each ball became a prefabricated component with its shape, texture, and thickness already built in. The custom guide brings consistency to the cuts, while differences between brands and states of wear remain visible across the finished shoe. Some sections appear bright and nearly untouched. Others arrive faded or scuffed, giving the upper an irregular surface shaped by the ball’s earlier time on court.

SLICE turns the curved shell of a used tennis ball into a footwear component

SLICE keeps the tennis ball composite intact

The shoe responds to a waste stream created partly by the tennis ball’s own construction. Its felt covering is tightly bonded to the rubber beneath, making the two layers difficult to separate through standard recycling systems. Balls also lose their regulated bounce relatively quickly, even as the rubber body and textile surface remain physically intact.

Project materials cite an estimated 400 million tennis balls produced each year, with only a small portion entering recycling streams. Existing programs often grind used balls into granules for court surfaces, flooring, or molded products. SLICE follows another path by keeping the composite together and using the ball’s geometry as part of the shoe. The source object stays legible, and the method avoids reducing it to an anonymous raw material.

custom 3D-printed guides hold each ball in place during the cutting process

discarded balls wrap directly around the foot

The prototype’s appearance comes directly from this assembly process. Curved yellow sections overlap around the toe and heel, while white seam lines interrupt the surface like fragments of a larger drawing. The shape remains broad and slightly bulky, closer to a material study than a streamlined performance sneaker. That visual weight helps explain the construction at a glance.

Photographs show the shoe worn on a tennis court, suggesting that Isfahani has moved the idea beyond a static model. Its longer-term performance still sits outside the available project information. Questions around traction, water absorption, repeated flexing, and felt abrasion would need further testing before the system could move toward broader production.

a blade follows the guide to divide the sphere into repeatable curved sections

a wearable prototype built through subtraction

SLICE currently exists as an experimental footwear project and a 2026 James Dyson Award entry. Its custom guides point toward a process that could be repeated across a supply of collected balls, though larger-scale manufacturing would require a faster cutting and sorting system. Variations in felt condition and rubber thickness could also affect how each section behaves once assembled.

The project’s strongest gesture is also its simplest. Isfahani treats the tennis ball as a piece of engineered material that already has form, resilience, and a familiar visual identity. One precise cut opens that sphere into a set of curved building blocks. From there, the shoe grows directly from the object being reused, with every fuzzy strip making its origin easy to read.

variations in wear give each section a different texture and shade

project info:

name: SLICE

designer: Soroosh Riazi Isfahani

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