Just throwing this out there.
Haven’t started photographing my knives yet, but from past photo work I used to do, this stuff was must have all over the studio:
http://www.amazon.com/Loctite-1087306-2-Ounce-Fun-Tak-Mounting/dp/B001F57ZPW
Shelf life may be forever. I have 10 year old fun tac laying around pliable and tacky.