A rope of entanglement looks just like any other hempen rope about 30 feet long.

Upon command, the rope lashes forward 20 feet or upward 10 feet to entangle a victim. An entangled creature can break free with a DC 20 Strength check or a DC 20 Escape Artist check.
The rope has AC 22, 12 hit points, and hardness 10, and it has damage reduction 5/slashing as well. The rope repairs damage to itself at a rate of 1 point per 5 minutes, but if a rope of entanglement is severed (all 12 hit points lost to damage), it is destroyed.

Prerequisites: Craft Wondrous Item, animate objects, animate rope, entangle.
Cost to Create: 10,500 gp, 840 XP, 21 days.