The next step was to mount the claws to a ball-bearing track that could be hooked to the back of Nate's forearm. The track was created from a sliding keyboard tray. The slider on the track was modified to be much shorter, and use only 8 ball bearings. Bolts were put through the slider on the track and then some galvanized metal was bent and hack-sawed to make the right shape for attaching the first claw.
Full story here.
Link is worth clicking on. This guy actually made a home constructed Wolverine costume, complete with retractable aluminum claws. The slider/arm/weapon imagery reminds me of DeNiro's jury-rigged spring holster in Taxi Driver.