An offline computer, running ubuntu, would be one way to securely generate a wallet:
Ensure the wallet is created with a pass phrase, dump the keys (and be sure you have the private keys all written down/printed correctly) then wipe the computer HDD.
(don't use an SSD, since most people don't understand how to properly wipe an SSD)
It's simpler to just remove your hard drive and use a live OS, especially Tails, since Tails will automatically delete all session data.
Live linux with no HDD has the obvious issue that you can
NEVER reboot the computer or allow a power failure to happen, until you have fully verified you have the keys correctly on some other media.
Instead, as I suggested, having it temporarily on a HDD, in a password encrypted wallet, allows you to safely decide when you no longer need the computer wallet.
You should point that out if you are going to tell people to use that option.
And I would never print a private key, who knows what sorts of backdoors and security vulnerabilities a printer might have?
Who knows what backdoors and security vulnerabilities every motherboard in every computer might have?
So you shouldn't use any computer?