Table of Contents
Why you need this BlockMIT Jig
Your Bitcoin seed phrase is the only thing standing between you and permanent loss. Paper burns at 451°F. Floods destroy it. House fires happen. If your seed phrase is on paper or in a digital file, it’s one disaster away from gone forever.
The Blockmit jig makes it easy to stamp your seed phrase into standard metal washers — the kind that survive house fires, floods, and 50+ years of storage. No special skills, no expensive tools, no excuses.
This is the simplest fireproof Bitcoin backup solution available. At $4.99, there’s no reason not to.
What you need to get started
The Blockmit jig is the alignment tool. You’ll also need:
- Metal washers — 24mm OD (outer diameter). Get them on Amazon here
- Letter/number punch set — 1/8″ (3mm) size. Get the punch set here
- Hammer — any steel hammer, 1-2 lbs
- Hard surface — concrete floor, anvil, or steel plate
That’s it. Total setup cost under $30. Protects a lifetime of Bitcoin.
Need the washers in 1-inch size instead? Check out our CC 1-inch Washer Jig — fits standard US hardware store washers.
24mm vs 1 inch — which do I need?
| Jig | Washer Size | Where to Buy Washers | Best For |
|---|---|---|---|
| Blockmit Jig (this one) | 24mm OD | Amazon (link above) | Original Blockmit spec, slightly smaller form factor |
| CC 1-inch Jig | 1 inch OD | Any hardware store in the US | Easier to source washers locally, 16 alignment spots |
Both work. The Blockmit jig is the original format. The CC jig uses washers you can buy at Home Depot today.
What’s included
- 2x Blockmit washer jigs
- Two jigs included in case one gets damaged during stamping
- Punch set and washers NOT included — see links above
Shipped from Colorado. Bitcoin accepted.
How it works
- Place a 24mm washer into the jig slot
- Position your letter punch on the first marking spot
- Strike firmly with a hammer
- Advance to the next spot, repeat for each letter of your seed word
- One washer per seed word — 12 or 24 washers for a complete backup
- Store in a fireproof safe, safety deposit box, or buried steel container
Full visual guide: DIY Seed Phrase Backup Tutorial — Estudio Bitcoin
Why buy from CryptoCloaks
- Bitcoin-native — we use what we sell. Self-custody is core to everything we do.
- Ships from Colorado — next business day, no overseas wait
- Bitcoin accepted — pay in sats
- 25 reviews at 4.88 stars — real Bitcoiners, real results
- 2 jigs for $4.99 — one for the job, one backup in case of a missed strike
Also check out our Seedor Safe seed storage for an engraved stainless steel alternative — no stamping required.
FAQ
Does the Blockmit jig come with washers?
No. Washers and punch set are sold separately. You need 24mm OD metal washers and a 1/8″ (3mm) letter punch set. Links above.
Is this fireproof?
The jig itself is 3D printed plastic — not fireproof. But the washers you stamp are steel, which is fireproof. The jig is just the alignment tool. Your finished backup washers are what survives a fire.
How many washers do I need?
One washer per seed word. A 12-word seed = 12 washers. A 24-word seed = 24 washers.
What punch size do I need?
1/8″ (3mm). This is the size that fits the Blockmit jig slots correctly.
What’s the difference between the Blockmit jig and the CC 1-inch jig?
The Blockmit jig uses 24mm washers (order online). The CC 1-inch jig uses standard 1-inch washers available at any US hardware store. The CC jig also has 16 alignment spots vs the original format.
Does CryptoCloaks accept Bitcoin?
Yes. Bitcoin native. Pay in sats.
What are the exact dimensions?
See pictures below.
Jasen Hardman –
Haven’t actually stamped with them yet but I don’t see why I’d have any issues. They seem to be made of strong, hard plastic and be durable. They look like they are 3D Printed, which isn’t a bad thing, it’s good. These are unique items and a smart idea. If you are looking for a cheaper alternative to store a mnemonic all you need is these, some washers and a nut and bolt and a stamp kit. You could find a place to bolt them like inside of bed frame or truss in the attic are a few ideas. You can even buy nice fire proof titanium washers if you needed.
David Anderson –
It would be nice if the Blockmit could be made to accept 5/64″ sized stamps…these are much easier to find than the 1/8″ stamps. 24MM washers also seem to be somewhat rare… The basic Blockmit jig is a fine idea and well-executed, but perhaps it could be better standardized for North American hardware.
Kidwarp –
Loving my 2 jigs. Fast shipping. I will be getting more for gifts. Make sure to get stainless steel washers and hardware!
Nikos j –
Cryptocloaks team super helpful, explained what I also need to buy with the blockmit jig.
Roy David Lester III –
Very easy to use and quite helpful when stamping washers for a cold storage option. Love the product and can’t wait to try more from Crypto Cloaks!!!
Tatum Turn Up –
Only reason that I don’t give the full 5 stars is because the stamp slot is a liiiiittle tight on some of my stamps. I was 100% able to work through this, but was a tad annoying once you get to about the 15th word. Now, mind you, some of my stamps from the same set were actually a little loose, so a slightly wider slot may be too much for those, but who knows. Still got the job done. Just be sure you get washers that fit flush with the inside diameter of the very base. I’m glad they sent me two because I was an idiot and got washers that fit inside the larger of the 2 diameters and it jacked up both my washers and my jig. Live and learn, baby!
JBOI –
Had to purchase 5 stamp sets before I found one that fit. The link in the description is old, the 1/8in version is unavailable. Link below is the one that fit the jig.
https://www.amazon.com/dp/B073S3HXSZ?psc=1&ref=ppx_yo2ov_dt_b_product_details
Ben –
A 24mm stainless steel washer is too small for these – they fall right through the jig’s hole. The quality of the jig itself is fine, but don’t look for 24mm washers. You’ll need slightly larger ones.
John (verified owner) –
Perfect for its intended purpose. The washers I bought fit perfectly.
Anonymous (verified owner) –
Works as advertised. Cheaper than Amazon. Happy customer