I built this unit from a kit to capture liquid drop splashes.
The breadboard construction was very straight forward and the
kit made it much easier than my sound trigger, which was built from scratch.

I purchased the kit from: http://www.hiviz.com/
They have lots of project kits and prices are very reasonable.

Falling drops of liquid pass between the two sensor prongs. After an adjustable delay, the
circuit is closed to the PC (or shutter) cable.

I placed the sensor in a separate unit with a magnet clip, thinking
that it would be more portable and keep the main electronics away from the liquid.
The output cable I used connects to my PC flash socket, but I think
that I may add another cable which will be used with my camera
remote release. I think the camera/flash setup may be easier
to operate if I control the shutter instead of having to have
an open shutter in a very dark room while triggering the flash.
I used an external 9v battery clip. This eliminates the need for an on/off
switch and eliminates the concern for corrosion of an internal battery.