A phillumenist. The hobby is called phillumeny or phillumenism.
A catapultist.
onithbfdbvb
I would call him a hobbyist.
dumb
A button collector??
normally .you call one .a letterologist.
a hoarder x)
Graphologist comes to mind or autograph hunter.
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.
An Arctophile.
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.