If you can make a key file You can put it on a removable sd card and make a keydrive. This introduces a nice air gap to the key, only needing to be broken when unlocking the drive.
There are better ways, often the the key can be stored on a hardware token(yubi key etc... ). which presumably offers additional security guarantees around copying the key. but a keydrive is a very easy way to start.
There are better ways, often the the key can be stored on a hardware token(yubi key etc... ). which presumably offers additional security guarantees around copying the key. but a keydrive is a very easy way to start.
Off tangent(I doubt you will be using openbsd), but the openbsd encryption layer offers some nice features around using keydrives, http://www.openbsd.org/faq/faq14.html#softraidFDE