Technical drawings, material specifications and information regarding standard parts can be found in the designated folder.
Adequate personal bitcoin security is a daunting challenge - one that will not forgive many mistakes. Every user’s situation regarding technical understanding and personal priorities, threat model and risk tolerance is fundamentally unique which renders generalized advice insufficient at best, dangerously confusing at worst.
To achieve a level of security you can feel comfortable with you must find the right trade-off between cost, privacy, complexity, and failure tolerance.
We cannot tell you what is best for your individual situation, but we can do our best to provide tools to aid you on your journey. The first of these tools is the SEEDMINT.
The SEEDMINT is a tool designed to easily secure your 12 or 24 bitcoin backup words (mnemonic seed phrase) on highly durable V4A stainless steel washers.
Using the included punches (4mm numbers & 2mm letters/numbers) you can stamp the index number (01 to 24) as well as the significant characters (first four letters) of each word onto one washer. This will result in 12 or 24 stamped washers.
Additional washers can be stamped with any relevant information you would like to secure in combination with your seed. This additional information may include but is not limited to: master fingerprint, derivation path, wallet name, passphrase, multisig scheme,...
The stamped washers can be held on a 316L stainless steel screw, fastened by a self-locking nut and stored in a secure location as an ultimate backup.
The above description is the use case we envisioned as a basis for the design of the SEEDMINT and is merely a recommendation. At the end of the day, it is up to you which information you would like to stamp on the washers and how you choose to store them.
Click "view code" on the Top to see all files
In the CAD folder you find the complete design in different format types .zip for Inventor 2019 and .f3z for Autodesk Fusion 360 (which doesnt cost anything for personal use)
Here you find the PDF drawings of the single pieces and a parts list.
This are links to the letter and number stamps used in the current Design
Parts to buy: (just paste the description into a search engine to find local sources)
| Amount | Description |
|---|---|
| 4 | cylinder head screw DIN 912 M4x20 |
| 2 | flat knurled screw M4x10 |
| 2 | high knurled screw M5X12 |
| 2 | parallel pin ISO 8734 2m6x20 blank |
| 1 | high knurled screw M3 (thread shortened) |
| 1 | spring plunger with thread locking GN 615.3-M4-k-PFB |
| 1 | parallel pin ISO 8734 3m6x12 blank |
| min. 24 | washer DIN 9021 6.4 A4(316L) or titanium grade 2 |
| 1 set | number punches 4mm |
| 1 set | letter punches 2mm |
The "original" SeedMint was tinkered without any references or drawings at all. Just for the love of handcrafiting things that I consider useful. But only after somebody asked me, if i would make plans for such a Jig available, so I thought if only one person would get value from this, it would have been worth while making those plans. This has also been the first time I have heared about Blockmit - quite ignorant as I'll admit..
The Jig is intended to be used with 2-3mm letter- and 4mm number punches on an M6 stainless steel washer with an outer diameter of 18mm. Just use a screw and a nut to hold them together. More solutions will follow.
Any contribution and/or feedback is greatly appreciated.
follow us @SeedMint21 on twitter for updates