In the previous log, I had finished soldering the PCB, and tested it outside of the project box.
I then took the PCB, the perf board with the buttons, and put it into a project box I had ordered specifically for this project. This was the project box, which included a custom PCB to fit into the box.
I then had to squish the wiring, the alarm, and the PCB into the project box, which proved to be a little bit of a challenge. I managed to get it, but really had to work to fit it in, and bend the wires in the right way.
Then I screwed it shut and tested it out! Works like a charm.
The completed project: