As others have said, www.bitcoinpaperwallet.com is great for having an encrypted Private Key that needs to be unscrambled.

However, if you want a really trustless system, then I would suggest you go to www.bit2factor.org and use the Two-Party Escrow tool. Your friend would use a passphrase that only they know to create an Intermediate Code which they send you.  You would use that a intermediate Code to create an Address, an Encrypted Private Key, and a Confirmation Code, all of which you send back to your friend.  (You can print the Address and Encrypted Private Key on any paper wallet design that is out there.). Your friend can check that the Confirmation Code matches the Address and Encrypted Private Key with their passphrase. Finally, when they want to import their Private Key, they would use their passphrase to de-crypt the Encrypted Private Key.