With a bit of development, we could make the Bitcoin Coin much smaller.

https://drive.google.com/file/d/1IGpS2MN89_z2QuH4N4MmeRJFwuZeHAtz/view?usp=sharing

There will soon be Bitcoin Coins as small as 20 mm in diameter. The nice thing is that very little nylon material can then be used, which means that the physical tokens can be produced very cheaply.

The picture shows a few levels with 20, 22, 24, 26 and 28 mm diameter. Next to it is one quarter dollar, one cent and one dime for size comparison.

I would be very interested to know which size(s) you would prefer. I look forward to your response.

Just coated with a different printer (Mimaki), still a bit wet but here is the first result:

https://drive.google.com/file/d/1eBSnZWLpySKb0Kj2thQ-e4xb33QvtCwR/view?usp=sharing

Please let me know if you're like it & interested to get some of this kind of print.

Many thanks to Mark Zeller for the invitation to this forum of collectibles!

I'd like to report a few technical considerations that led to our Obol wallet.

The token shown is an evolution of a technique that involved breaking a plain nylon coin in half to access an inner code.

The coin would have been a possible alternative to the metal piece with paper code plus adhesive seal.  As is well known, the latter could have been spied out unnoticed back in 2013 (CoinDesk, Aug 13, 2013 "Defcon hackers crack physical bitcoin coins").

Unfortunately, this predecessor showed that the code, which was formed as a raised 3D font, could be seen very well in the CT scan. Further, the token also had to be quite large in diameter for the elongated alphanumeric code sequence to be printed in sufficient quality.




Anyway, it was possible to use additive manufacturing for sealed codes years ago, provided you liked big Mickey Mouse tokens and CT scans of the private key didn't worry you.