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 a Oak magic wardrobe flatpack from scratch gives a profit of: -1,588
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.