So, if you're a Star Trek fan, then you'll have heard of transparent aluminum and as it turns out, it's now a thing. Aluminium Oxynitride is also called transparent aluminum and is marketed under the name ALON as well. It's quite bulletproof, is lighter than most bulletproof products, and if it could be shaped into an empty sphere like you describe in your comments, would pretty much fit the brief of all but the programmability (and perhaps the maneuvering to the assigned location). Fortunately, because it doesn't have to change shape we can add to the inside of the sphere a very simple solution to this - a computer. Hell, even just a NavMan if all you need it to do is get somewhere.
Getting it to be able to move around as well is a bit tricker, but you could put external 'fans' or turbines on it to get it to move in a desired direction, especially when alfoat, meaning that you pretty much have all you need, and a little more. Because it's (mostly) transparent, you can even tell at a glance whether the bubble is taken or not. Of course that works both ways as it means that pirates can pick and choose what bubbles to go after, but getting into them is going to be harder because... Well, transparent aluminium.