⭐ Merited by o_e_l_e_o (4)
Check out Aaron Toponce's implementation called Deckware.
Now this seems interesting. The underlying method of Lehmer code certainly looks preferable to Ian Coleman's implementation, although it requires using a third party's code. Quote
Although the code is simple, the whole point of using a physical method of entropy generation is to avoid doing this, and if someone doesn't trust /dev/urandom to securely generate entropy, then relying on code written by one person and (as far as I can tell from a web search) not reviewed or even discussed by anyone else ever is a bad idea.
that's probably because using a card deck for entropy is a very niche thing and not many people are willing to go to the effort of doing it. certainly not your average joe bitcoin user. so who else is there? just tech nerds maybe.Quote
I suppose it would be possible to calculate your code manually using an airgapped computer and a simple calculator package, but the chances of making a mistake with this process are very high.
flipping a coin is simplest and probably superior to dice and cards. i think we can agree on that. dice probably come in 2nd due to their simplicity compared to cards. cards are last because it takes special processing to get your entropy. assuming one does not backup their entropy, they can use the card deck as a store of their entropy which you really can't do with dice or coins. unless you want to store 256 pennies stacked up. and then good luck not spilling them when you try and read them out. 
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And as I said earlier in the thread, given that I have no formal training in cryptography, I cannot rule out that there is some glaring vulnerability of which I am unaware. I am not willing to risk the safety of my coins by using something which I cannot verify. I'll stick to my simple, secure, quick, and easy coin flips. 
240 bit numbers there just aren't as many of them as there are 256 bit ones. you made that point loud and clear. and you're probably right that coin flips is superior method over everything. but for someone that has a bunch of card decks lying around they might as well play around with the possibilities
