I used the tripod to take a photo with the hood up and one with the hood down. I then cut the engine bay out with the hood up and overlaid it on the hood down photo and saved it. I then reopened the photo with the hood down and used the box to cut and paste the fresh hood over the modified original picture and used something like 50% opacity to make the effect. What I would really like to do is blur the level of opacity around the engine bay to give it more of an x-ray effect highlighting the center of the engine and not all of the surrounding components.