I threw these together for a couple of my custom instances for players and had the thought to share them. They are not mirror images of each other and are about the size of a classic dungeon entrance. (See photo)
These can be modified with more rocks/stalagmites, and you will need to add teleporters of course. You may also want to place blockers to prevent players from stepping thru them by accident.
These can be modified with more rocks/stalagmites, and you will need to add teleporters of course. You may also want to place blockers to prevent players from stepping thru them by accident.