The Cryptosteel Cassette can be purchased at cryptosteel.com. It’s a stainless steel device that comes with prefabricated letters. Claims to be resistant to physical damage, including fire, flooding, corrosive conditions, electric shock and impact from accidents.
Just requires a flathead screwdriver to unlock and start sliding in the pre-stamped metal pieces. I will note that the steel letters are not quite as nice as those provided with the Billfodl. This is because they are stamped on each side which results in the steel pieces being slightly curved; some of them are sufficiently curved as to be more difficult to slide into the slots of the wallet. The Billfodl letters are laser engraved rather than stamped, thus the pieces are completely flat. This is the only noticeable difference between the two products.
Heat Stress Test
Held up quite well and almost all of the letters stayed in their slots. Perhaps this is the trade-off to be made for better heat resistance — it’s more difficult to get the letters into the slots but as a result it’s also less likely that they’ll fall out under stress. Nevertheless, some letters did fall out and I also consider this to be a catastrophic failure due to data loss.
Corrosion Stress Test
Was unaffected by the acid; looked the same as after the heat test.
Crush Stress Test
Rail-based devices are not robust when it comes to handling deformation of the device without suffering from data loss. Even slight deformation results in letters falling out of their slots. By the time I pried it back open, pretty much all of the letters had fallen out.