Save youre superglue tips, well those glue applicators you can buy seperatly is actually what I used. I just guessed at the scale and cut the tip in three peices. First I cut the big end and then the little. I then took what was left over from the second cut and stuck in the big part of the speaker horn to serve as the cone inside the speaker. Sorry if this does not make since Im half asleep. Any way here is some pics.

interesting idea..... looks effective also.

Creative use of alternate supplies. I like the idea, and the additional detail is going to help your diorama.

In looking at just the speakers they look a bit thick. Once the whole diorama takes shape they won't be as prominant and the affect won't be as 'powerful'.