I should have posted a bigger picture, as this is exactly the kind of stickers I have used. Also important they have a serial number.
Don’t worry, I am going to explain everything in the English version of my thread, which has HYGE pictures.

Bear with me.
I am going to translate the whole bunch of informations in English.
Today I added a paragraph regarding... Glitter Nail Polish... wondering if it is available in RED ^{(not sure I am getting this joke, btw)}

As far as I know, Bitcoin is the only crypto natively supporting multisig. Multisig are actually more se ire than single sig, only lacking a truly idiot proof interface.
I have great expectations for Taproot to make degrading multisig easy to implement for the idiot user (like me).
Something that was implemented by GreenAddress, for example, with a custom software implementation. 
A degrading 3/4 multisig would be my perfect ideal setup.


I have to deliver then.
I’m on the case. Latest addition to the italian OP are beyond my comfort zone.

That's not true, I've seen it in Byteball (now Obyte), which actually supported it from it's official wallet. From what I remember, this was much more idiot proof by default than manually setting it up in Electrum. It's been a few years, but what I remember is linking the different wallets from inside each wallet, which worked nicely.

Electrum is confusing: If you create a multisig wallet, you can't even save your incomplete wallet before you have the master public keys from all other wallets too. I tested it earlier today, and it's disappointingly labour intensive.

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I just realize talking about multisig in a topic about steel washer backups is slightly off-topic. And of course setting up multisig is much less labour intensive than 3D printing and hammering words into steel I've spent hours setting up a secure wallet and backups in the past.

You can buy it on amazon or ebay but you can't remove residue with void message so easy and that's the whole point.
It is easy to customize it with different unique shapes, and I was not going to use this for bitcoin seed words but for regular envelops with paper documents.
You can also order this tapes with custom design, so for fillippone I would add custom ferrari drawing with electric power, or you can send them any design you want.

My assumption for those stickers has always been that it's not easy to replace them. Removing residue shouldn't be that hard (using a solvent).
I've seen laptops with an anti-theft-sticker which covered a "Stolen Property" warning burned into the plastic. That would make it much harder to cover up tampering.

On paper, I agree that it's going to be very difficult to remove any sticker residue without leaving permanent damage.

Thanks for sharing that capsule file. Compatibility should be possible by getting the right washers for the capsule & then generating a jig for those washers using my new openSCAD file that I posted the other day.

Also this idea of mixing filaments is pretty cool; reminds me of fillippone's glitter nail polish idea. It will be pretty hard to replicate the 'mix' 1:1 another time. You can simply pause the print at a random time, switch the filament and repeat it however often you want.
Adding a design into the file itself would also work, but it'll be easier to replicate.

Actually, 3D prints will be one of the surfaces where it's hard to get off such a sticker without damaging the plastic, since it's usually soft and reactive to lots of chemicals. Prints also have lots of small ridges where the adhesive can get into nicely, so no chance of simply peeling it off cleanly either.

As per nail polish, or any other entropy-related scheme, you are supposed to take a picture (and safely store) to check against to the seal while opening it.

Progressing with the translation of the thread. Should soon land.

Since we're on the subject of printing custom capsules with multiple colors: how about making the capsules for each part of the multisig storage line up? Say you have 3 cylinders with metal washers. When you put those 3 cylinders together, a matching pattern occurs. That way you don't need to remember the exact details of each cylinder, but you do need to get them all together to check if any tampering took place.