Nowt really, closet thing is probably tools as i’ve got 3 large tool cabinet/chests, one for bike stuff, one for car stuff, and one for “other stuff”. I doubt even that could be termed a collection as the contents get used frequently.
Don’t really do any other collections as i hate clutter/shite lying around and every few months have a clearout, I stay in a 1bed bungalow so space is at a premium and i have very minimal other stuff, my entire life at age 45 would fit quite comfortably in a small transit van. (apart from my tool cabinets)
Oh…just remembered – I collect reg numbers of vehicles that either cut me up/endanger my life on the bike and when/if i get the chance to pull them up about it at some future point i am quite polite about broaching the subject with them, what i do next is dependant on their reactions.