Chain links are actually sort of tricky to model for a plastic extrusion printer like the Makerbot- there aren't very many variations that don't feature too extreme of an overhang anywhere. This one has been working so far, inspired by http://www.thingiverse.com/thing:519. The main difference in mine is that both the 'ball' and 'socket' of each link face the same direction, so a pieced-together chain has links that alternate direction (Check out the pictures). I'm not sure how excited one should get over this, but it does give the chain a sort of flattened, "belt-like" quality that might lend itself to use as some sort of belt that can be attached to a large wheel? Note that each link can only pivot about 35-40 degrees before it becomes in danger of detaching from the link behind it. I plan on creating a second version that addresses some problems:

-Deeper gap between the "fingers" of the fork, to increase range of pivot. -Higher "thumb" section to increase pivot in opposite direction. -Stronger fork tips that don't break as easily... Maybe just make them thicker.

I'm including both the .stl and Maya .ma files so that anyone can have their way with this thing. This was modeled with an extrusion printer in mind, so throw it in your Makerbot! Takes about 17 minutes to print.