Got the main elements (2 sets) for the latest Woody this morning. The rail will be fitted to a 1/4" threaded rod through the upright running on 2 1/4" ball bearings. LEGO gear on the other end driven by a worm gear.
Unfortunately, couldn't get the bits from my previous supplier (email@example.com) but Applebridge (firstname.lastname@example.org) were able to cut these out for me. If you are thinking of doing something similar I can recommend both.
Focus rail only £8.70 from ebay!