Living Hinge As a Wearable

A living hinge that can be worn as a bracelet or watch strap.

A living hinge is a pattern of cuts that lets a stiff sheet bend. My design here can be worn on the wrist as either a bracelet or a watch strap. The watch component represents a watch face and is included to demonstrate how the design would function as a watch strap.

Living hinge cover
Living hinge prototype
Demo of wearing on the wrist. See the video version here.

Final Version: dimensioned.

Before the this version, I asked classmates for help, and they reminded me to use sketch dimensions. I stopped copying by hand. I set the gap widths as explicit dimensions, drew reference lines, and mirrored the pattern across them so both halves matched. The spacing came out even.

Caption photos easily. On the left, a road goes through a tunnel. Middle, leaves artistically fall in a hipster photoshoot. Right, in another hipster photoshoot, a lumberjack grasps a handful of pine needles.

Failed attempts

Version 1: a curve that wouldn’t cut.

I started with a complicated curved pattern. I built it by projecting and copying geometry back and forth in CAD, following suggestions from AI tools. I didn’t go to TA hours or ask classmates. The file couldn’t be cut.

Version 2: diamonds placed by eye.

I switched to a simpler pattern of diamond-shaped slats and gaps. I copied and pasted the shapes and estimated the spacing without setting any dimensions or constraints. This version cut and it bent. But the gaps weren’t evenly spaced, and it looked uneven, which also made it bend unevenly and broke easily.

Caption photos easily. On the left, a road goes through a tunnel. Middle, leaves artistically fall in a hipster photoshoot. Right, in another hipster photoshoot, a lumberjack grasps a handful of pine needles.

Apart from the unevenness, the small diamonds were causing problems during cutting. The diamonds fell out of the sheet often, and even caused the laser head to shift, which ruined the cut and was dangerous.

The small diamond would fall out of the sheet during cutting, which caused the laser head to shift and ruined the cut.

What I learned.

Version 2 worked well enough that it would have been easy to stop there. The unevenness came from how I drew the pattern, so the fix was in my CAD workflow and not in the shape. I would also have gotten there sooner if I had asked people earlier.