You will need transparent PNG images to build your customizer. Here's a quick video explaining the basics:
Download example images
These images were created by cutting out photos (one for each view) with Adobe Photoshop.
You will notice that many parts are white. That's because the customizer will apply the color variations dynamically on those images.
These images were created with 3D rendering, basically the creating two-dimensional transparent png images from a 3D model.
For this customizer, there are images for every variation, for each part. The customizer will alternate between those images based on the customer's choices.
Click here for everything you need to know about getting your images ready for your customizer.