Yes, drop boxes constructed that way shall be Centurion acceptable, and indeed that's my tutorial
The boxes don't actually need to open. As i handmade mine, the fit is really tight and the airlock is enough to secure the halves together, but some glue them, some use velcro, or magnets.
Edit: all the pics on my tuto are now hosted on flickr rather than imageshack. Still don't know why i used this terrible host in the first place...