As the large playback-only soundboxes worked fine at MERL, and the small size of the last version made it very difficult to get all the components in, the sound recorder has been scaled up.
The speaker on the last version was crudely glued to the bottom, and didn’t really fit properly; the new one has a proper piece to hold the speaker with a grill to protect it. The bayonet fitting idea was copied from the top piece of the old design.
The joint between the bottom piece and the main body is less obvious than the top/body joint as the edges aren’t rounded off, but it should still be secured with glue, tape, screws, etc to stop users from undoing it.
It was noted that it would be nice to be able to ‘point’ the device at the desired sound, like a microphone or dictaphone. The previous version had the microphone mounted in the side of the main body. The new one has a socket in the centre of its top, with a small grill to protect the microphone.
As the new case is so much larger, this should allow for more complex electronics (perhaps a microphone preamp to clean up recorded sounds a little), and larger batteries, as well as being easier to construct.
It will take considerably longer on the 3D printer though. It’s unlikely that more than one case could be printed simultaneously.