Paper burns, fades and gets soggy. The BlockMIT stamps your seed words into stainless M8 washers: cheap hardware-store parts that turn into a backup no house fire, no flood and no decade of attic storage can touch.
Paper is gone at around 230 °C — a normal house fire runs far hotter. Stainless steel washers sit at a melting point roughly six times higher and come out of the ashes readable.
Flooded basement, damp attic, twenty years in a drawer: ink runs, thermal paper turns blank, stainless steel does not care. Stamped letters are physically punched into the metal, not printed on top.
A stack of washers on a bolt looks like leftovers from the workshop. No logo, no branded steel plate that tells a burglar exactly what they found and what it might be worth.
Stainless M8 washers from any hardware store — one per seed word, so 12 or 24, plus a few spares for practice. You also need a set of letter punches and a hammer.
The BlockMIT holds the washer and lines up the punch. The punch guide for M8 washers does the same job for freehand stamping — no slipping, no crooked letters, no ruined washer.
One word per washer, in order. The first four letters are enough — no two BIP-39 words share them — so you punch less metal for exactly the same backup.
Slide the washers onto a bolt in the right order and drop the stack into the Washer Stack Box. Store it somewhere dry and boring — and put a second copy in a different building.
Not included: the washers themselves and the letter punches — both are cheap standard parts and you probably want to pick your own font size anyway.
Stainless M8 washers (one per word), a set of steel letter punches and a hammer. The washers cost a few cents each at any hardware store; a punch set is a one-off purchase you will keep forever.
It protects against fire, water and time — not against a person holding the washers. Anyone who finds and reads the stack can spend your coins. Hide it well, and consider splitting the backup across two locations.
Both work the same way, you just need one washer per word. A 24-word seed simply makes for a taller stack and a longer evening with the hammer.
No. You get a piece of tooling in the post; the stamping happens at your table, offline, with nothing connected to anything. We never want to know your words — and neither should any other vendor.
Yes — Lightning and on-chain, with 7 % off the price. Card and PayPal work too. Shipping starts at 3 € within Germany; the rate for every other country is listed in the shop.
The evening you actually need your seed phrase is a bad evening to find out the paper is unreadable.
