I have that mouse
I also needed to post because this is interesting and I want the updates

If I was going to print them, I would probably boot from read-only media on a machine without network connectivity. My statement about less than 1MB of memory implies the printer does not have network connectivity either.

For the dot-matrix, there is the possibility of lifting the image from the ribbon, but it gets recycled/reused within minutes. A Laser printer may have a similar problem with the drum, but those tend to have over a MB of memory anyway.

forprivate key security you could use am small chip on the card which needs some kind of pin (with self destruction .

so we have to possibility to name you a few recipient adresses and write our wallet+pin to the card ourselves.

(ok in the wild we would need some kind of terminal to do the actual payment)

i love your idea

Well I was hoping it would come friday, due to weekend and holidays it'll be tomorrow hopefully.

To address concerns.

It does not do and dot matrix or inking, It runs on vectors and as such, the engraver has no real physical observations to get codes. I'll do the engraving offline on a different computer than my main machine. It probably doesn't have a terribly high on board memory. It's possible its fed via usb and would have no on board memory. If not I'll do everything in reason to assure you the codes are safe. If you can tell me a way to wipe any cache I'd be happy. This solution is made so that you don't have to worry about the sent coins. You can send me anything to be engraved. If I make a private public keypair, I can personally assure you that you can trust me and I'll happily use references on the forums that have personally met me if you have any concerns. Feel free to encrypt info should you want to send me personalized info. I'm here to serve you so you can get engraving done without anyone other than a single user on the forum.

So... this thread got my imagination running...

Not so far future... You get notified that your uncle you didn't even know about died and your presence is required for reading of his will. You soon find out that your uncle was one rich bastard but all he left you was a small diamond. So you decide to see how much the diamond is worth and take it to a specialist. While looking at the diamond the specialist notices there is an engraving on one of the sides of the diamond. Looking closely you realize it must be a QR code. The QR code is your uncles private key for his wallet containing hundreds of thousands of bitcoins. All in a small diamond

I've already found one for you. No need to go anywhere.
http://www.bluenile.com/emerald-diamond-1-carat-or-less-good-cut-g-color-if-clarity_ld01435822?rf=pd

dimensions are 75x50mm and a public key qr code should be very scannable and nice as it will be a white bg with black engravings on acrylic

update!