A key enthusiast is one way to identify them. There is no actual term to refer to someone who collects keys out of enjoyment, but if they keep the keys out of fear that they may find a use for them after throwing them away, they are potentially a compulsive hoarder.
Cagophilist
someone who collects umbrellas
A badge collector.
A paper collector
you guys sound like little kids
A locksmith. Home depot can make copies of keys.
A catapultist.
onithbfdbvb
I would call him a hobbyist.
dumb
A button collector??
normally .you call one .a letterologist.
You would call them a locksmith. Locksmiths make keys for everyday use.
a hoarder x)
Graphologist comes to mind or autograph hunter.
Someone with too much time on their hands and too much space?
A key maker. -.-
An aquarist is someone who collects fish in aquariums. They can also simply be called fish keepers. Some collect a variety of fish, while others specialize in a few kinds.