BlockMIT metal backup tool for your seed words.
Paper is gone at around 230 °C and a house fire runs far hotter. Stainless steel melts only far beyond that and comes out of the ashes readable. The BlockMIT is a small 3D-printed tool for stamping your seed words into stainless M8 washers with letter punches: it holds the washer firmly and guides the punch, so nothing slips and every letter comes out straight and legible.
How it works: drop in a washer, stamp letter by letter, next washer. One word per washer, and the first four letters are enough because no two words on the BIP-39 list share them. Twelve or 24 washers on a bolt in the right order, done. A stack of washers on a bolt looks like leftovers from the workshop, no logo, no branded steel plate that tells a burglar what they have found.
Not included: washers, letter punches and hammer. All standard hardware-store parts; the washers cost a few cents each and a punch set is a one-off purchase. You need stainless M8 washers (24 mm outer diameter), one per word plus a few for practice.
Important: this backup protects against fire, water and time, not against people. Anyone who finds and reads the stack can spend the coins. Hide it well and keep a second copy in a different building. For the finished stack the shop has the Washer Stack Box, for freehand stamping the punch guide. The design is open source, the stamping happens at your own table, offline, and we never learn a single word.
