MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
Yes, print out multiple copies and glue them end to end to increase the length. If you print the rack gears with lower density you can stack more of them without the turbine needing to work much harder since they will weigh less. In my pictures/video I have both 2 and 3 racks attached. A light breeze can lift up to 5 or 6 of them (low density) and as weight increases you'll need additional wind force to move the turbine. You'll eventually reach a point with any material where it can't handle the stress. I'd be interested to see how well an aluminum print would work.
To increase the amount of weight the turbine can lift, you would need to increase the gear reduction by adding/changing gears.
My goal with this model was to make it almost completely 3D printed, but you might want to adopt a cable/weight system for bigger projects like what is described at http://www.gravitybattery.info/