Some cutters (or associates of cutters) are known as trophy hunters — individuals who build up large collections of body parts, most commonly testicles. In the same way that a big game trophy hunter will have a case or room full of animal parts, a trophy hunter as the word is used here may well have a room full of jars of body parts (or a refrigerator full).
The legality of trophy hunting is usually somewhat grey, but ultimately in most areas owning body parts is legal. The issue is how you obtain them! Because of that, most trophy hunters tend to be very discreet, rarely show their collections to strangers, and guard their contacts closely.
Trophy hunting in regards to body modification is not unusual historically. When the Maori were "discovered" by the West, a seedy trade of decapitated tattooed heads erupted, with wealthy Westerners proudly displaying the "primitive" mokos to their socialite friends. Similarly there exist collectors of tattooed and skull shaped corpses dug up in Peru, as well as collectors of tattoo skins.