I assume your kit is meant for "average" users? If so, isn't the software arguably the most delicate component of this? Since I do not see that it has been explicitly mentioned here, your kit should include something like a bootable DVD or USB stick with secure software pre-installed on it, together with easy-to-follow instructions on how to verify the checksum. Also do not forget that since you are booting into a more-or-less known state it is absolutely essential to introduce enough entropy before generating any random numbers, etc.
Very good suggestions proff!
Indeed, it is meant for the newbie, not even the average user. Once you have more than say $500 you want to keep it offline, so that's the target customer/user.
My initial thought was to have the user download the software from openpaperwallet.com, go offline, run it and print. A key part of this project will be the user instructions, which I am writing now and will hope to get help illustrating.
Now, if people think that download-offline-print is too insecure or prone to hijacking, we could add USB keys into the
retail product, but that would be up to individual resellers.
Since I hope to be the first reseller of these as kits, let me ask the community here: USB stick or download?