Actual shim stock is available... with lots of choice in material, thickness and so on.
Search on line for, "shim stock".
Beer cans are lined with plastic and are thin, easy to cut, very strong and hold the shape you want pretty well.
I'm sure that soda cans are similar, but I'll never know.
Right, so here's the real reason for this post!
I have a roll of actual duct tape (that's spelled: D-U-C-T) lying around.
This stuff is a roll of aluminum meant to seal ducts air-tight.
One side of the aluminum sheet is coated with a quality adhesive.
You can find this high quality duct tape in big-box home improvement stores locally
and, of course, on line.
It works well for shimming non-load bearing stuff and might work for your camera mount.
