I found this topic from the youtube video of the guy who flipped the coin 256 times in 2015 year, and he made a link to this subject.
I developed a project (bitcoin Visual private key generator) for making this process faster.
The decsussions of the project are here:
https://bitcointalk.org/index.php?topic=5187401The project site is here:
https://btckeygen.com