Engineering Records · 3D Printing & CAD Design
Designing a TPU Wrist Key Strap
Taking what I learned from the bracelet designs and applying it to a flexible wrist strap built around a different use.
From CAD to Physical Wrist Strap
Comparing the printed wrist strap directly to the CAD model it came from.
Designing a TPU Wrist Key Strap
The wrist key strap came directly out of what I had been learning from the bracelet designs.
Instead of starting from zero again, I wanted to see how much of that work could transfer into a different flexible product.
Starting From What Already Worked
The bracelet project had already forced me to think about flexible geometry, repeated surface patterns, curved shapes, and how TPU behaves after printing.
The wrist strap uses some of those same ideas, but the shape and purpose are different.
Instead of wrapping around a wrist as a closed bracelet, the strap needed to create a flexible loop that could be grabbed, carried, and attached to something else.
Changing the Geometry
The new shape meant I couldn’t just stretch a bracelet and call it finished.
I needed to think about the loop profile, the narrower connection point, where the material would bend, and how the patterned surface would continue around the part.
This was a useful example of taking something I had already learned and applying it instead of treating every new CAD model as a completely separate problem.
From Model to Physical Part
One of the things I like about this design is how easy it is to compare the CAD model directly to the finished part.
The overall shape comes through clearly, but the printed TPU also adds things that are hard to judge on a screen.
The flexibility, thickness, surface feel, and the way the loop actually behaves all need a physical prototype.
Printing More Than One
Once the individual strap was working, I arranged several on the build plate together.
That let me use the same design as another small experiment in batch printing.
The idea is still simple, but it starts moving the workflow away from making one prototype at a time and toward making a design repeatedly.
Where It Fits
I don’t see the wrist strap as a completely separate project from the bracelet work.
It’s more useful as evidence that the techniques from one design are starting to transfer into other things.
That’s the direction I want this whole project to keep moving.
The goal isn’t just to learn how to make one specific object.
It’s to get better at designing.