Q25 for SMARTISH (in-house)
Industrial Design | Product Development | CMF | DFM
We designed this case with a side-loading card slot mechanism that allows storage of 1–3 cards plus cash, while keeping moving parts minimal. The card compartment is tensioned to grip contents securely and avoid rattling, yet permit quick access.
During development, the case went through multiple prototype iterations to refine both the material composition and the card retention mechanism. Early versions struggled with either insufficient grip, allowing cards to rattle, or excessive tension, making insertion and removal impractical. Achieving the correct balance required experimenting with different wall thicknesses, durometer ratings, and tolerances at the slot interface.
The complexity was compounded by the integration of softgoods into an otherwise rigid TPU shell. Unlike homogeneous plastics, softgoods introduce variables such as stretch, compression set, and bonding behavior that interact differently with injection-molded TPU. Ensuring durability at the junctions where flexible textiles meet molded plastic required repeated testing of adhesives, overmolding strategies, and surface treatments. The result was a hybrid system where the softness of the textile complements the structural rigidity of TPU, delivering both secure card storage and long-term material stability.
Design Details:
Impact protection is addressed through air-pocket corner geometry that functions as localized shock absorbers, and the shell is validated via a 6-foot, 50-drop test onto concrete to validate resistance against frequent drops. The case adds approximately 4.5 mm to the back thickness, striking a balance between structural protection and slim form factor.
Kicktsand
Surface treatments include a textured finish on the sides to improve grip without causing adhesion to fabrics, and precision cutouts maintain full access to the device’s controls, ports, and camera interface. The included card-slot doubles as a rigid kickstand, enabling hands-free viewing without introducing hinge joints—this is achieved through the structural stiffness of the card holder itself.
Material choice, mechanical tolerancing, and stress distribution (especially around the card slot and kickstand interface) seem to be prioritized to maintain durability under cyclic card insertion/removal, bending stresses from the stand function, and edge wear.
