An oak kitchen table flatpack can be made at a workbench (oak workbench or better) in the workshop of a player-owned house. This requires 32 Construction, uses 3 oak planks, and gives 180 experience. The flatpack can then be used on the table hotspot in the Kitchen while in building mode. This requires no Construction level and gives no experience.
The cost of making and selling an oak kitchen table flatpack from scratch gives a profit of: -1,656
After completing the hard Fremennik achievements, they can also be traded to Advisor Ghrim in exchange for 84 coins being added to your kingdom's coffers in Miscellania. See Flatpack: Miscellania reselling for details.