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.
Step 2: Setup
Camera: To stabilize the camera I used an old but strong aluminum tripod, the stiffer the better.
Plexiglass: to hold the plexiglass still I used a swivel vise from OSH that I clamped to my table.
The macro setup I used is a m42 mount macro bellows with a 50mm enlarging lens attached, any lens can be used but an enlarging lens is nice because it has a perfectly flat plane of focus. As a result of this flat focus plane it is critical you get the plexiglass perpendicular to the camera otherwise some parts of the image will be out of focus.
My flash is pointed down towards the cases because you want the light to reflect off the colorful objects and show up in the droplets. You can position the background however you like but I found that the object directly below the lens affects the background color, while objects on the edges change the color on the edges of the droplets.
Step 3: Taking the Shot
I put the camera in mirror lock up, bellows at about 5", f16, 1second shutter speed, ISO 400, 1/32 power in the flash, and used a remote to ensure stability. You can play with background and flash positioning to change the look, the color directly below will be the background color and colors on the edge will affect the edges of droplets. Just play with it until you're happy with the shot that's the beauty of digital photography.
To get my exposure right I first changed my shutter speed until the droplets were a little bit underexposed, then added flash power as necessary until the background was bright but not blown out.
Step 4: Post Processing and Conclusion
I ended up using these for backgrounds so I cropped them to 16x9 and wrote a tasker app to select from 10 case matched colors. This is triggered either by a widget or contact with a certain NFC tag that is attached to the box my cases stay in. You can do whatever you want with them, with a nice camera they will looks good on almost any display.
So give it a shot and post pictures of your results.