I what to built a set of gears in a single printing, but when I have tried it has not worked. Basically I want 2 interlocking rings, and it looks like it can be done from the examples. With Blender does is have to be a single object? Or can I create the cog, then add the framework.
You can print fully functional mechanical constructs in 1 go. However, you have to keep a very close eye at the specifications of the material you want it printed in. If two parts are too close together they will be fused together. There is a lot more info available on the tutorials page. https://www.shapeways.com/tutorials/index Take a look under "Advanced tutorials: mechanical parts & designing for 3D printing" You can also get a feel for it by looking at a few models from the 3D parts database. https://www.shapeways.com/themes/3dparts There are a few mechanical parts there. You can download them and have a look.