Fair warning: I am a complete novice in 3-D printing. This will, hopefully, be the first thing I've ever printed.
I want to make a Constant Velocity Joint for a camera stabilizer I'm making. I've been looking at different options, and it seems that a double cardan joint would be easiest to design/make/print. However, the intended use involves force being applied along the shaft, into the joint, which I think in a double cardan will cause "buckling" (forcing the joint into a 90° zig-zag).
Also, perhaps I'm wrong, but I don't see it rotating very smoothly (pretty essential for camera stabilization.)
So my next idea is a Tracta type, with bearings. The question is:
Can you print bearings inside their housing? or do movable parts have to be printed separately?
Based on information provided in the comments I can say that yes, you can technically print bearings inside their housing. However, you must consider the capabilities of the technology.
Typically an FDM printer, such as a MakerBot Replicator, can yield undesirable results depending on how small you need the objects and how close each object is to another (ie bearings to the housing/each other). If you have a dual-extruding FDM printer, you could utilize a second support structure material. For example, you could print the bearings/housing in PLA and print the raft/supports using water soluble PVA. This provides a solid structure while printing without worry of having excess material in the housing (defeating the purpose of a bearing).
On the other hand, using the powder printer is most likely your best solution for creating the bearings (and less frustrating). Naturally, you will not need to worry about support structures as there is support inherently created as the powder is lain out for each layer. You just need to be sure that the tolerance of your model adhere to the capabilities of this machine and its post-processing.
Regardless of which technology you use, be sure that your design incorporates a means of allowing support material to be taken out after the print is complete.