Before typing in your actual passphrase download this page to your trusted computer first. Examine the Javascript code to exclude any security concerns. Don't run this HTML-site on a server. Just open it with your browser locally.
This page will encrypt your passphrase visually. The form below generates two images, which only together can reveal your passphrase (or anything else). One image resembles the encryption key - the other one your passphrase. The encryption image will be applied on the transparent acrylic block and decrypts all colored sheets attached as long as they were generated with the same encryption key. The image resulting from your Nxt passphrase in the "passphrase" box will be applied on the fluorescent acrylic sheet(s). Hit "Make Images" and position the two cryptoimages. Then Laserprint the window named "stream + ciphertext" on the transparent film, that came with your NxtSafe. Cut out both frames and the inner area and apply the adhesive films on the acrylic sheets. Positioning the sheets in a way, that the printed cryptoimages match exactly will reveal your passphrase.
Of course you could do all this without my stylish acrylic sheets, but it's much harder to lose a colored block of glas, than these cryptofilms alone.
If there are spaces at the ends of the lines, or blank lines at the bottom, that will enlarge the pattern that is generated. If you want, you can remember the password, use a passphrase of all spaces, print out the "stream", and give that to the recipient. With that he will be able to decrypt all passphrases, that were encrypted with the same password.