The Swiss company SMD Security Printing Sàrl has released (https://www.icynote.ch/) a cold bitcoin wallet in the form of a banknote. Circulation of Icynote was 100,000 copies.
This is a crypto wallet made of high density polyethylene measuring 158 × 70 mm. Icynote banknotes can withstand temperatures from -40 to 60 ° C, resistant to water and mechanical influences.
Wallet addresses are created by a hardware random number generator. Developers destroy printer hard drives after printing. Moreover, they use special printing inks and apply holographic images on banknotes according to Swiss standards.
At the pre-sale stage, the company received 200 orders for more than 1,000 banknotes.!