Housing items based on gear. The item or items would have to be at 100% repair and lose all materia melds and spirit bond, cleared of dyes, etc., and probably have to be Inn Room Compatible (for uniformity), but Then you could have something like a Display Piece for a hand full of items, including Suits of Armor (combines with a Mannequin recipe for display), Arcanist spell Books (table top item), and Weapons Racks (weapon rack recipe) or Wall Mounted Swords/Shields/Axes etc.
The Housing Version of the items could be said gear item + some Restoration materials and crystals/clusters (like vintage gear), then to Get your gear item back, you use a "Desynth" process and it automatically (100% success) spits back the main item. That's probably the easiest way to convert an equipment item into a housing item and back again ^_^
Craft-able display Gear would be tradeable, while unique items (Atma, Relic, etc.) would not.