The pictures that had the same drop colored several times looks difficult to do with a sound trigger.Perhaps a laser trigger?
Is it difficult to build one?
Take a look at the site's instructions for building these triggers, they don't seem too dificult, you may need a little electronics experiance and a soldering iron. There are plans for light triggers too...
To make a laser trigger is no harder than making the light activated trigger, except you are going to narrow your sensor to the beam of light instead. You can make it an ifared sensor as well so you can do it in daylight, not in total darkness.
Your imagination is the only thing holding you up.