Escalation

We have an ongoing pen pal exchange with our friends up in Boston (if you haven't already, read part one, part two, and part three). After a several month hiatus, we got a device in the mail from them. When we plugged it into a battery, this happened:
When decoded, the lights spelled out a URL in morse code (we were about to visit them and go to a Final Fantasy concert together, hence that particular video link).

A while ago I saw a tutorial on making woven bead bracelets, so I decided to give it a go with our response. I wove a braille link into a bracelet, and I think it turned out pretty well:

The whole bracelet

Close up of the pattern

We were nervous about the security of sending such sensitive information in the mail, though, so we decided to send it to them in a locked box. But since we can't trust the mailman, we didn't want to mail them the key. So we mailed it to them like this:

Thankfully, they knew just what to do, and a week later we received it back like this:

(we ended up switching our gold lock to the other side before we mailed it to them)

We then removed our lock and sent it back to them, so they could remove their lock and open it upon receipt:

Thank you, Diffie and Hellman!