obsidian invention number 1 features a nice room that can be completly remodeled by a flip up a switch... the default setting is a storage room but once you flip the switch....BOOM it becomes an empty room able to be redecorated again it is just that simple. please note though this is better if placed under ground

Additional Notes

the switch on the left next to the tnt detonates the tnt and the switch on the right rasies and loweres the tnt, inorder to reset place the sticky piston's in the required slots, place the tnt under then go all around the pistns top with redstone wire, finally place the switches in the default places (look at pictures)