Take the length of rubber tubing and cut four or five louvers on one side (see figure 7). You can cut the louvers using a scissors or wire cutter. The louvers force the rubber tubing to collapse to one side (directional) when compressed. Next take the 6-32 machine screw and nuts. Position one end of the nitinol wire under the screw head and tighten one nut up against it. Then remove 1/2 inch of insulation from the 22 Ga. wire, wrap the portion of un-insulated 22 Ga. wire around the 6-32 screw under the first nut. Tighten up the second nut against the 22 Ga. wire.

Thread the open ends of the nitinol wire and 22 Ga. wire through the rubber tubing and then through the hard plastic tubing. The 6-32 nut holding the 22 Ga. wire and nitinol wire should be flush with the top of the rubber tubing. Secure the base of the rubber tubing to the top of hard plastic tubing with tape (masking, scotch or electrical).

Attach the free end of the nitinol wire to the 8-32 machine screw and nut in a similar manner as described before. The 8-32 machine screw and nitinol wire assembly must be positioned at the base of the hard plastic tubing, without any free space in-between. You may have to collapse the upper rubber tubing while attaching the 8-32 machine screw to get it position correctly.

Attach the PWM circuit to the nitinol wire (via the 8-32 machine screw) and the free end of the 22 Ga. wire. By rotating the potentiometer you will be able to bend the the upper rubber tube portion digit. The digit will bend in the direction of the louvers. Reducing the power allows the digit to straighten out.

If you place three or four of these digits in a circle, with the louvers pointed toward the center, you will have a rudimentary gripper.