Crane for DSLR

I have been working recently on building a custom rail slider for my black magic cinema camera, needless to say I am being very careful to make sure it is stable.

The idea crossed my mind however that as light as DSLR rigs can be (assuming you are using a small prime lens etc) it might be possible to build a robotized crane relatively cheaply using 3D printed parts to connect carbon fiber or steel rods.

I am going to start playng with the idea in software, but thought I would start a thread here and see if anyone has built something similar, maybe throw some lessons learned my way. The major difference between this and many of the robot arms I have seen in the forum is that this would need to be able to handle a significant amount of weight, and ideally would remain rigid without power (or at least gracefully close). I am wondering if pneumatic driven joints would be the best way to go, or if there is another simpler method for ensuring that the robot doesn't come crashing down when the arm is extended and power is removed?

I could mount this on a tripod, but I think it might make the most sense to simply have the crane on a weighted base, something very heavy holding it down, maybe just barbell weights?

Lots of exploration still to do