You're perusing the auction house for costume armour and accessories, you see something you like and you would purchase it if it was just in your desired colour, it's regal but you want heavy! You keep looking... No luck.

If only there was a way to change its colour.
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My idea is to have a little stall next to Bechamel where you can place your costume pieces and accessories to convert them to a different theme for a price. 10k a costume piece for example and maybe half that for accessories (that are not already applied to armour for simplicity).
With a caveat that whatever costume piece or accessory you convert will bind to you, because honestly if you're going through the effort of changing the colour you must want it for yourself right?
Event specific cosmetics cannot be colour-converted to or from without the use of a ticket, which could be pulled from prize boxes maybe.