The technical concept of a composite image is like this: Each answer in your product can have an image assigned. When your customer selects answers, these images will be stacked together to form the product image. When your customer changes selections, the system updates the visualisation by switching out images.
Important notes on managing images
Use the same dimensions for all images and position the shown object carefully so it blends well with the others.
Use PNG images with transparent background
Balance image dimensions and quality at your discretion.
To enable composite image visualisation, go to your product and section Visualisation and select Composite Image. If useful to you, you can upload a so called Base Image that will display beneath all dynamic images.
Note: Be sure to save your product before heading to the next step.
Go to the edit screen of a question and open an answer that should add an image to your composite image.
Upload an image. With Visualisation Stacking Order you control in which order images should be stacked. Higher numbers will be stacked higher (possibly covering images with lower numbers).
After you added all your images you can see the transitions while you configure the product.