I have used the T-nuts for several pinhole cameras. I install them with the T part toward the camera by drilling partway into the wood with a 13/16 Forstner bit and finishing the hole with a 5/16 drill. That way the tripod screw pulls the T-nut tighter into the wood. If you are worried about it rotating just add a drop of epoxy glue to it when you install the T-nut. I have attached the block of wood to a plastic Polaroid camera with silicone rubber and have had good luck with that.
Jim Stewart
