Continuing on the Coinkite theme, I also got their
Opendime product, a method of physically transferring "small" amounts of bitcoin off-chain with zero knowledge of the private key by any party. The 1st Bitcoin Bearer Instrument or just call it a "Bitcoin Stick," as they refer to it.

There have been attempts before at producing a trust-less physical wallet, such as the Casascius coin, but the Achilles heel was always the nagging uncertainty that the manufacturer could retain the private key information and then spend whatever was loaded onto it after an exchange.
What CK did with the Opendime was to utilize a secure element on the device, which provides secure storage and true random number generator, that doesn't contain a private key when shipped to the original owner. The initial setup process requires that the device be plugged into a computer, which comes up like a USB drive, and user defined entropy in the form of files are dropped into the Opendime folder. Once enough entropy has been added by the user the device hashes that with the device's entropy to generate the public/private key pair and stores that private key in the secure element onboard the device.
Once initialized the device displays a web page with the public key and QR code for loading and verifying funds with a second party for transactions. The fact that the person accepting the loaded device is able to verify the funds on the spot and has confidence that the person they received the funds from can't steal it back later means there's no need to do an on-chain transaction, which eliminates the associated fees and confirmation time prior to finalizing the business transaction.
When the time comes to move the funds off the device in an on-chain transaction the owner sticks a pin through a marked hole on the back to pop a resistor off the circuit board to reveal the private key when plugged into a computer. This alters the device in such a way that it cannot be reset and the funds on the private key must be swept into another wallet to avoid being stolen. The device is useless after this and can be destroyed or disposed of, it's a one-shot deal.
Coinkite doesn't recommend storing "large" amounts on the Opendime device, mainly because there is no way to backup the private key. Unlike every other hardware wallet device, which allows the user to backup their keys with a seed phrase, there is no way to do that with the Opendime without compromising the zero-knowledge aspect of the device. So, while one could use it for long-term cold storage, there's no way to recover from loss or damage and one needs to adjust the amount stored on the device accordingly.
Honestly, I personally don't have a good use case for this device at the moment, but I can imagine situation where this could be invaluable.