For most people, the best metal seed phrase backup is the Cryptosteel Capsule Solo, the strongest all-round performer in Jameson Lopp's published stress tests. If you want something lighter and simpler, the Billfodl holds a full 24-word phrase in a flat steel case, though it scored poorly on crush resistance. If you want titanium, the Cryptotag Zeus Starter Kit is the premium option. If cost matters most, a plain steel plate you stamp yourself is what Lopp calls the best value. We weighed published heat, corrosion and crush grades, the maker specifications reported by reviewers, and the listed prices. Nothing here was tested by this blog, and every figure names its source.

Why metal at all? Your seed phrase is the list of 12 or 24 words that can rebuild your wallet on any device. A wallet setup screen suggests writing it on the card in the box, and that card is paper. Coldcard's guide to storing a seed phrase puts the problem in two numbers. Paper ignites at about 233°C. Residential structure fires often reach 600 to 1,000°C. Stainless steel melts at about 1,400°C and is essentially impervious to water. Coldcard's view is that paper is fine for small test amounts and metal is for savings.

Best for most people: Cryptosteel Capsule Solo

The Capsule is a steel tube. You slide lettered steel tiles onto a core, one character at a time, and screw the shell closed over them.

It wins this slot on the independent evidence. Jameson Lopp's metal seed storage reviews have put 75 devices through the same heat, corrosion and crush tests. The Capsule earned an overall A-, with an A for heat, an A for corrosion and a B for crush. That is the strongest combined record among the products in this roundup.

Material and specs. According to Bitbo's 2026 comparison, the shell is AISI 303 steel and the core, separators and tiles are AISI 304 steel, with a fire rating of up to 1,400°C (2,500°F). Besides standard BIP39 phrases (the 12- or 24-word format nearly every wallet uses), it accepts SLIP39 shares and other key formats. CaptainAltcoin's 2026 review gives a capacity of 123 characters and a weight of 540 grams.

Price. The listings disagree slightly: $109 on Lopp's review page (undated), $99 in Coinpaper's roundup of February 24, 2026 and in Bitbo's 2026 comparison, and $101 for the Capsule Solo in CaptainAltcoin's 2026 review.

The real drawback. Capacity is counted in characters, not words. A 24-word phrase spelled out in full will not fit in 123 characters, so you record a shortened form of each word. The sources here do not spell out the abbreviation rule, so follow the maker's instructions to the letter. Placing tiles one by one also gives you many chances to slip, and CryptoAdventure's 2026 roundup notes that transcription mistakes cause more real losses than fires do.

Skip it if you want something light enough to forget about or you would rather not spell anything letter by letter.

Best for a slim, tool-free backup: Billfodl

The Billfodl is a flat steel case holding a sheet of laser-engraved letter tiles. No stamping and no tools are needed.

Its case for this slot is size and simplicity. Bitbo lists it at 100 x 60 x 6 mm and 170 grams, roughly a third the weight of the Capsule. It is made of 316 marine-grade stainless steel, rated fireproof to 1,200°C (2,192°F), and holds a standard BIP39 phrase of 12, 18 or 24 words.

Price. $99 in both Coinpaper's February 2026 roundup and Bitbo's 2026 comparison. Lopp's review page lists it at $55, undated. Check the current price before you buy.

The real drawback. Lopp graded it C overall. Corrosion resistance was an A, heat a C and crush a D, the weakest crush grade in this roundup. His summary notes it has survived documented real-world house fires, but a falling beam or a collapsed floor is exactly the kind of force a D grade warns about.

Skip it if your backup will sit somewhere a structural collapse is plausible, or if you want anything beyond a BIP39 phrase stored.

Best for titanium: Cryptotag Zeus Starter Kit

The Zeus uses titanium plates. According to CryptoAdventure's 2026 roundup, it records each word by its index, a number standing for the word's position in the BIP39 word list, instead of spelling it out. CryptoAdventure credits it with low spelling risk for that reason.

Price. Coinpaper's February 24, 2026 roundup lists the Cryptotag Zeus at $139, the highest price among the eight products it surveyed. It does not say whether that figure is for the Starter Kit specifically.

The real drawback. The case for titanium here rests on a claim. Coinpaper describes "superior heat and corrosion resistance compared with standard stainless steel options," but the sources available for this article include no Lopp grade for the Zeus, so there is no independent crush or fire result to compare with the Capsule's A-. Check Lopp's site for a Zeus entry before paying the premium. If it is there, that settles the question.

Skip it if you want the best tested result for the money. On the published evidence here, that is still the Capsule.

Best for the lowest cost: a plain steel stamping plate

This is the oldest approach. You take a solid steel plate and punch each word into it with a letter stamp or a center punch.

Lopp's verdict across 75 devices is blunt: "The best bang for your buck are the single plates." He names Bitplates, Blockplate and Steelwallet as the best-value examples. A single plate has no tiles to fall out and no case to crush open. CryptoAdventure adds that deep stamping or punch marks tend to hold up better than shallow etching in extreme conditions, so strike hard.

Price. The sources here give no price for a single stamping plate kit, so compare the current listings yourself.

The real drawback. A stamp is permanent. A misspelled word cannot be corrected, so you need a second plate, and how legible the result is depends on how carefully you work.

Skip it if you are not comfortable swinging a hammer at something that has to be legible in 20 years.

How to record the phrase without creating a new risk

A metal plate only protects the words you put on it. Most of the risk sits in the half hour you spend copying them, which is part of the broader discipline covered in our crypto security basics.

  1. Copy the words straight from the device

    Work from the hardware wallet's screen, in private, with no phone or camera pointed at the table. Spell every word against the BIP39 list your device uses.

  2. Check the plate against the device

    Coldcard's guide says a backup check should confirm the words are legible and that they regenerate the correct addresses. Use your wallet's restore or verify function to confirm the plate rebuilds the same wallet before any meaningful amount goes in.

  3. Store it apart from the device

    A thief who finds the device and the plate together has everything. Coldcard's minimum standard is two copies in two separate locations: one at home, one off site in a bank box or with a trusted family member.

  4. Keep any passphrase somewhere else again

    If you use a BIP39 passphrase (an optional extra word that opens a separate wallet), Coldcard's inheritance guide says to store it at a different physical location from the seed. Either one alone cannot open the funds.

  5. Never make a digital copy

    The Alcazar Security guide lists phone photos, screenshots, cloud drives, email drafts, notes apps and plain text files as unsafe. A password manager belongs on that list too. Every one of them puts the phrase on a device that is online.

  6. Inspect it once or twice a year

    Coldcard recommends an annual or semi-annual physical check for legibility and wear.

A strong backup cannot fix a weak seed

Steel preserves whatever you engrave, including a seed that was badly made. In July 2026, Coinkite disclosed that a firmware bug in some COLDCARD devices had generated seeds from weak randomness. According to its security status page, attackers then rebuilt private keys offline and stole funds, without ever touching the devices. Cointelegraph reported confirmed losses of 1,778 BTC (about $112 million) as of August 21, 2026.

The wider lesson is about where the device comes from. Coinkite's own advice is to verify the signed download before generating a seed. Buy any hardware wallet only from the maker's own store or the maker's own Amazon storefront, where the item is sold by the maker. Never buy one used, from a third-party seller or "pre-configured", because a device that arrives with a seed already chosen belongs to whoever chose it. Our guide to wallet types explains what a hardware wallet does if you have not chosen one yet.

What to buy

  • Cryptosteel Capsule Solo: for most people who want the best published test grades.
  • Billfodl: for a light, tool-free BIP39 backup, if a weak crush grade is acceptable where you store it.
  • Cryptotag Zeus Starter Kit: for buyers who want titanium and index-based recording, and can accept the lack of an independent grade in the sources here.
  • A plain steel stamping plate: for the lowest cost, if you are careful with a punch.

If none of these fits, for example because you want the Zeus but need an independent grade first, wait until Lopp's reviews include the product you are considering. That is the one published source testing them all the same way.

Questions buyers ask

Coldcard's guide says paper is acceptable for small amounts and test wallets, and metal is for savings and large holdings. If the wallet is meant to hold Bitcoin for years, it is savings.

No. The Alcazar Security guide calls this the biggest mistake people make, because wills usually become public record during probate. Keep the plate in a secure location and give the will or a separate letter only the instructions for finding it.

No. Coldcard's inheritance guide says to store the passphrase at a separate physical location, because the seed and passphrase together open the wallet and neither does alone.