I have spent the past few days using the 3D printed prototype and like the overall design and look. Some small tweaks to be made before the machined metal version, but no major reworks planned.
Most of the past few days have been evaluating material options for both the wallet and the bands. For the wallet, I have been torn between titanium and aluminum. Titanium is fantastic, super strong, but expensive. Aluminum is lighter, not as strong, but much more economic. Looking into specific aluminum materials, the normal 6061 is just not going to do it. I continued to dig and ran into something used in aerospace. Its called 7075-T6 and it if it is good enough for Musk, it's worth looking into. Turns out it is about as strong as some steels but is lightweight and economical to use. I plan on moving forward with this material for the metal prototypes in the next few weeks. Doing so should keep the wallet in the $40 range.
Next up was the bands...
My first prototype was a hand sewn elastic band. It was a pain to make, frays, and is not secure enough for what I want to do. My goal is to be able to clip this to your athletic shorts and not worry about your card falling out. I tried out two different materials, EPDM and silicone. Both provided a ton more security and each had their pros and cons.
EPDM (Pros) Got their name because they were used by the Army Rangers. Extremely tough, resistant to just about everything. (Cons) Not as aesthetically pleasing as the silicon counterpart.
Silicone (Pros) Strong yet able to mold into custom shapes such as wedding rings. Multiple color options with better finish. (Cons) Slightly more difficult to remove cards from the wallet and had one snap on me during testing.
There is still more testing to be done, but I am leaning towards the EPDM bands. I would plan on including a few of them so there were no worries about them wearing out. To further put those fears to rest, regardless of the band material I plan on guaranteeing for life. They break, I will supply new ones free of charge.
Finally, I did test using the walled with the clip in shorts with both the silicon and EPDM. Nothing fell out of the wallet during a dance party with my 3 daughters, a crazy dinner, bath time, and putting them to bed. Suffice to say, the design is moving in the right direction.
Thanks everyone for the feedback so far and I will be providing more updates as the design continues.