wondrous item, rare
This object appears as a wooden box that measures 12 inches long, 6 inches wide, and 6 inches deep. It weighs 4 pounds and floats. It can be opened to store items inside. This item also has two Command words, each requiring you to use an Action to speak it.
One Command word causes the box to unfold into a coffin 7 feet long, 2 feet wide, and 2 feet deep. The inside is typically lined with cloth and is usually red, white, or black in color. The coffin can hold up to four Medium creatures comfortably.
The second Command word causes the coffin to fold back into a box, provided that no creatures are inside. Any Objects in the coffin that can’t fit inside the box remain outside the box as it folds. Any Objects in the coffin that can fit inside the box do so. Sleeping in this coffin allows you to gain the benefits of a long rest in half the amount of time usually required.