For all those themes already existing, make one for each citadel.
Make the skins a consumable usable by appropriate role, but anyone can preview.
Allow multiple skins to overlay with different levels of opacity.
Allow skin “effects” to be a purchasable skin layer- ripple, electric, gas cloud, mirror, battle damage, exposed circuits, mismatched armor plating, half of -insert ship- crash embedded into the skin, construction vehicles moving around, gardens encased in glass domes, space monster gnawing on the station, etc.,.