We had just four days to design, build, and test the circuit. 
There was no chance to make a printed board in such a short time
and we decided to put the components on a breadboard.

The echo was intended as an "electronic medal" and the electronic
components should be visible. Thus the breadboard was mounted onto
some stable board together with the speaker and some box for the
battery.

Thomas Falk contributed the speaker (and the battery). The plastic
box at the bottom contains the battery.