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. 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. 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.

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.

Maybe. But the whole point of the argument I'm making here is that I'm not a cryptographer, so I can't say for sure. And neither is anyone else in this thread, by the looks of things.

People without extensive medical knowledge don't tend to attempt surgery (unless they are very stupid), and so we shouldn't be attempting to create our own ad hoc cryptography, especially when there already exists better tried, tested, and verified methods.

Also, a slight niggle: You do loss a small amount of entropy (<1 bit) when you hash a string for a brain wallet.