Very cool, one way I would think to accomplish this is to take a separate photo of each gecko/ gecko foot on glass behind the same solid color background. Black works very well in this case. From there you could cut and paste the feet along side of each other, rotating them and what have you, without the background being disrupted. Too bad I only keep one species of gecko (gargoyles). Still I may have to try this some rainy day
Other factors are you can't use flash or a bright light directly on it or you'll get glare! And avoid seeing the reflection of the camera in the photo!