Blockstream Metal can be purchased at A rebranded Billfodl, based on open source Cryptosteel design. This stainless steel device comes with prefabricated letters. “You can then rest assured that our high quality marine grade 316 stainless steel will keep your seed safe against all the elements.”


Setup was straightforward — most of the time was spent finding the letters I wanted and in some cases I had to use a small screwdriver to keep all of the letters oriented straight in the rails as I was sliding it along.

Heat Stress Test

No data loss, all tiles remained in place.

Corrosion Stress Test

All of the rivets dissolved and thus the stacks of rails separated, resulting in all of the tiles falling out, causing catastrophic data loss. I spoke with Billfodl about this and they were surprised because the manufacturer has told them that the rivets are made from the same steel as the rest of the device. Hopefully they can determine what’s going on here; something about the rivets is clearly different from the rails and tiles.

Crush Stress Test

Already destroyed, but we know from the test of the Billfodl that the tiles would fall out after the device was crushed and pried back open.