Geo, collecting can be fun but you always find new things to collect if you are lucky. I collect doubles with different locking/opening systems. When I started I knew of four or five different ones. It seems like there are two dozen or more of them from the simple to vastly overly complex. I am sure a few remain for me to find.
I tried to collect all different species of ducks seen on the Chesapeake Bay and its surrounding rivers. I had a full cape head mount of each of them for my wall. Youd see just the front of the breast, neck and head mounted on a nice looking Walnut plaque with an engraved plate noting species, date taken and location. Had over two dozen mounted and my still to find list was getting shorter and shorter. I did it to make fun of my hunting buddies who lusted for that big buck mount for their walls. Had a real nice line of them on my gun room wall until I had an infestation of some bug which seemed to like them better than I did. Ended up throwing them all out which made my wife happier.