Even though I play Pathfinder, there's a new PF magic item called Folding Armor, that appears as an amulet hanging on your neck. With a command word the amulet 'unfolds' and like the armor from Stargate the movie, plates begin unfolding and forming into a full body suit of plate armor.
So not only can my anti-paladin sleep with no armor that can instantly become armor, but my character can attend public functions in fine dress - he's a nobleman afterall, but if there's a sudden need for combat, I utter the command word, and a round later, I can attack fully armored.
Perhaps you could import this item into your 3x campaign.
Folding Plate
Aura: moderate conjuration (summoning) CL: 10th
Slot: neck (brooch) or armor (unfolded) Price: 12,690 gp
Weight: - (brooch) or 50 pounds (armor)
This item normally looks like a heavy steel brooch or cloak clasp, often depicting a heavy helm or sturdy shield. On command the brooch transforms in a clatter of metal plates and panels to instantly cover the wearer into a complete suit of +2 full plate with the design of the brooch displayed on the wearer's breastplate. The same command word causes the armor to transform into a brooch. The item transforms only if the wearer's armor slot is unoccupied, thus it will not work if the wearer is already in armor.
Requirements: Craft Magic Arms and Armor; instant summoning.
Cost: 7,650 gp.
GP