Hole of Eno
This is a hole. It's a magic item made of negative space. The "hole" itself is an item. If you place the hole in your pocket, you now have a hole in your pocket. If you place it on a wall, the wall now has a hole in it, etc. The only clue that this hole is a magic, move-able hole is the dark ring around it on whatever surface the hole is on, and the vague scent of decay that seems to emanate from the hole.
The hole is just big enough to fit your hand through, and extends through surfaces that are 3 feet long, creating a tunnel. If placed into a solid material, like a creature's flesh or a solid mass of stone that is too thick to create a tunnel through, the hole instead creates a 3 foot deep cavity. If inside a creature or living thing, it won't deal damage or bleed, just appear as a hole. Items lift inside the hole when it is removed stay within whatever substance the hole was opening up before. The hole can also be placed on something in a smaller diameter, up to the size of a pinhole, whenever it is moved.
If the wall, ground, or subject hides a specific item (treasure chest, heart, etc.) then it will be within the hole when it is opened if the user of the hole sacrifices a prepared 1st level spell slot. People without magic spells cannot use this ability unless they find a way to power the magic somehow. Only one item can be appeared inside the hole when it is placed down and the placement doesn't have to be exact- the magic of the item creates the hole as it is needed.
The hole can be moved from surface to surface by anyone who sacrifices a 1st level spell slot to move it, or by using a secret command phrase which requires a full identify to uncover. The hole only exists in hole form; meaning if you want to carry it around, you need to put a hole in something until you need to move the hole to something else.