A teak magic wardrobe flatpack can be made at a workbench (steel framed bench or better) in the workshop of a player-owned house. This requires 60 Construction, uses 4 teak planks and gives 360 experience. The flatpack can then be used on a magic wardrobe hotspot in a Costume room to produce a teak magic wardrobe. This requires no Construction level and gives no experience.
The cost of making and selling a teak magic wardrobe flatpack from scratch gives a profit of -1,469 coins.
After completing the hard Fremennik achievements, they can also be traded to Advisor Ghrim in exchange for 225 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.