I have a home brew Game Camera. I use a section of logging chain to secure it to a tree, and the case has a hole in each side with a rubber gasket to keep out water. I wrap the chain around the tree, and each end goes into those holes, then it is padlocked inside the case. Then I have two smaller padlocks locking the case shut.

Worked well for me, and have busted a few people who tried to take it with pics.