This device is about ¾ inch across and can be made of ivory, bone, or any hard mineral.

It enables its possessor to put up a special wall of force 10 feet on a side around her person. This cubic screen moves with the character and is impervious to the attack forms mentioned on the table below. The cube has 36 charges, which are renewed each day. The possessor presses one face of the cube to activate a particular type of screen or to deactivate the device. Each effect costs a certain number of charges to maintain for every minute (or portion of a minute) it is in operation. Also, when an effect is active, the possessor’s speed is limited to the maximum value given on the table.
When the cube of force is active, attacks dealing more than 30 points of damage drain 1 charge for every 10 points of damage beyond 30 that they deal. Spells that affect the integrity of the screen also drain extra charges. These spells (given in the list below) cannot be cast into or out of the cube:

Cube Face	Charge Cost per Minute	Maximum Speed	Effect
1	1	30 ft.	Keeps out gases, wind, etc.
2	2	20 ft.	Keeps out nonliving matter
3	3	15 ft.	Keeps out living matter
4	4	10 ft.	Keeps out magic
5	6	10 ft.	Keeps out all things
6	0	As normal	Deactivates

Attack Form	Extra Charges
Horn of blasting	6
Wall of fire	2
Passwall	3
Disintegrate	6
Phase door	5
Prismatic spray	7

Prerequisites: Craft Wondrous Item, wall of force.
Cost to Create: 31,000 gp, 2480 XP, 62 days.