I've had great success making 'caviar' with sodium alginate and calcium chloride. I've used both an eye dropper and a Parmesan shaker (when I needed a whole lot of spheres). But I've never been able to make the larger spheres, sometimes referred to as ravioli. I've had them in restaurants as big or slightly bigger than a grape. What's the technique to get them this large? Anything in particular I need to watch out for?
Michael's answer is good, but I have an even simpler one.
Make your liquid. Now freeze it--ideally in spherical molds, but whatever works well for you.
Bring your alginate solution up to just below the boil--96-98C is perfect. Remove from heat, drop your frozen proto-spheres in one by one.
Note that this was our process for approximately tablespoon-sized spheres, and we used a silicone mold for freezing that was hemispherical. Larger spheres may not melt fast enough to react.