I chose to do this because I just got the galaxy s4 and ordered 10 cases for a couple bucks from China. Just for fun I wanted to change my background to match every case. To do this I used this technique with each case as the background.
Step 1: Equipment
Macro setup: Most important part of the shot, I used macro bellows with a 50mm enlarging lens, but you could use a diopter, extension tubes, or a dedicated macro lens.
Lighting: I used a canon 550ex but you can use normal lights with longer shutter speeds.
Plexiglass: This is the canvas for the droplets, I used 1/8" plexi but any clear scratch free material will work.
Spray bottle: Used to apply the droplets
Colorful background: I used cellphone cases, but you can use anything, Ive had success using thing like poptart boxes.
Remote: optional but to reduce shaking a remote is helpful, I used a cheap intervalometer.