Rigid carry cases for electronics provide protection against various abuse conditions such as impact loading and water damage. This small project looked to design such a case for the ColdCard.
The ColdCard is a bitcoin signing device / bitcoin hardware wallet. It is common to keep a microSD card in the device. Some users use more than one microSD when using the save passphrase to SD card feature.
Two versions have been developed.
- Fully Printed
- Modified Product
This version provides impact protection only (no gasket for a waterproof seal). It is printed as one part with a captured hinge design. The design is still in development and will be released soon.
Currently the design has capacity for a single SD card. The card slides from the oversized chamfered recess on the left hand side into the undersized recess on the right hand side where it is robustly constrained.
Modified Off The Shelf Case
This version provides both impact and water protection. It is an 'off the shelf' waterproof SC card storage container with a custom 3D printed insert.
SD cases available at low cost in many form factors. They are typically hinged, have a robust clasp, are often foam lined and have a silicone gasket. These features make them ideal as a platform for a quick DIY carry case.
The foam lining can be removed from one half of the case and replaced with a custom 3D printed insert which matches the profile of the ColdCard.
There is capacity to store 12 MicroSD cards & 6 full size SD cards in the original (unmodified) foam insert in the other side of the case. The foam gently presses on the face of the ColdCard on closing. The result is that the ColdCard is can't move, even when shaking the closed case.