First, you're gonna want to gather all the materials you need... PS3 controller, small philipshead(+) screwdriver, small flathead (-) screwdriver, toothbrush, utility knife, painter's tape, ziplock bag, latex gloves, any colors of spray paint you want
Step 2: Removing the Internals
First you'll want to use a small philipshead (+) screwdriver to separate the two halves of the shell. Once you take the back piece off, under the lithium ion battery there is another small screw that holds the motherboard in place. Take that screw out and put it somewhere safe. If you have a dualshock 3 controller, the vibration motors have little tabs that's hold them into place in the handles. Squeeze those and carefully pull the rest of the motherboard out. Don't mind the L and R buttons. They'll probably fall off, but that's okay. Once you remove that, take out the rest of the buttons and pieces such as the D-Pad and start and select buttons. Keep them in a safe place so you don't lose them. Also make sure to remove the clear LED plastic piece. You can get it out with a small screwdriver.