An oak magic wardrobe flatpack can be made at a workbench (Steel framed bench or better) in the workshop of a player-owned house. Like when making the normal Oak magic wardrobe, this requires 42 Construction, uses 4 oak planks and gives 240 experience. The flatpack can then be used on a magic wardrobe hotspot in a Costume room, either in building mode or not. This requires no Construction level and gives no experience.
The cost of making and selling an oak magic wardrobe flatpack from scratch gives a profit of: -2,172
After completing the hard Fremennik Tasks, they can also be traded to Advisor Ghrim in exchange for 112 coins being added to your kingdom's coffers in Miscellania. See Flatpack: Miscellania reselling for details.
See Magic wardrobe for a list of armours that can be stored.