SRD:Immovable Rod

Immovable Rod: This rod is a flat iron bar with a small button on one end. When the button is pushed (a move action), the rod does not move from where it is, even if staying in place defies gravity. Thus, the owner can lift or place the rod wherever he wishes, push the button, and let go. Several immovable rods can even make a ladder when used together (although only two are needed). An immovable rod can support up to 8,000 pounds before falling to the ground. If a creature pushes against an immovable rod, it must make a DC 30 Strength check to move the rod up to 10 feet in a single round.

Moderate transmutation; CL 10th; Craft Rod, levitate; Price 5,000 gp.