A technique we have been working on for about 5 months is making spheres. I saw this technique from moto restaurant in Chicago. This involves taking a balloon and filling it up with air so it almost pops. this stretches the plastic so it is easy to remove. You then fill the balloon with 60 cc of liquid. We have found that purees with high water content work the best ie.. carrot, watermelon, beet, tomato. You then add a small amount of nitrous gas to the balloon. This will force the ingredients to the outside of the balloon. You then roll the balloon in liquid nitrogen. This creates a hallow sphere. You then let the balloon temper in the freezer for 2 minutes. You can then cut the latex off leaving you with a perfect sphere.