As per the Vacumania website's essay "Collector vs User" a reasonable hobby context definition for collecting might be, "Accumulation' as a hobby or for study".
Let us call Pen Collecting, then, "The accumulation and study of pens in a goal-oriented fashion".
Collectors are not just hoarders, though some generic definitions allow for that and though no doubt some of the psychiatric dysfunction of hoarding is present for most of us.
Collecting can be done in a very generalized/eclectic fashion or in very focused fashion. One might want an example of every major pen series made during 1920-1980 from the top ten makers throughout the world. Or one might want to have every last Parker Vacumatic. There are no rules regarding what one seeks, though there without doubt are guidelines regarding pursuing well what one seeks: "Learn to grade pens", "Learn about potential parts mixes", "Learn market prices", etc.
Collecting any pen series to completion poses challenges. Besides just expense, some series offer hundreds of variants, progressive esoteric, many off-catalogue, with international variants to be found as well. The hunt can never be done , which of course might be part of the charm. What duck hunter wants to catch the very last duck?
So, we end up with mini collections, focused hoards defined by a common feature. While generally it does not represent just one's small sample of a large series ("here are my five Parker 51's"), even that is a potential definition. Usually, a linking feature defines away most of a large series. Thus, we have Canadian Parker Vacumatics with solid-gold cap-bands , or Wahl Eversharp pens done in Flamingo plastic, or Sheaffer pens in marbled blue plastic, something that defines a much smaller collection, even when complete.
As with most threads at Fountain Pen Board, the request for images of your mini collections is not meant to be highly regimented . It's fine if you want to show your five Parker 51's, even if the only linking features is being part of a series that has a zillion variants. But, if you can find something that tidies up the boundaries of that mini collection? All the better. Share if you care to what drew you to the subset of pens in your mini collections.
A nice mini collection is a thing of poetry, so let's consider this thread Ode to the MInii Collection
Let's see yours.