In a blender, puree blueberries with water, sugar, and fresh lemon juice. Strain mixture through a fine-mesh sieve, pressing with a rubber spatula to release as much liquid as possible; discard solids. Add water if needed to yield 3 cups.
Divide among ten 2 1/2 ounce molds; insert wooden sticks, and freeze until solid, about 3 hours (and up to 1 week). To remove, dip bottom of molds in warm water for 2 to 3 seconds.
This is delicious! I did not use the molds, but froze it in the ice cream maker. Also added 3 small, fresh basil leaves before puree.
I don't know if you're near a World Market (aka Cost Plus) but if so, they usually have a couple of molds over near the cooking section. :)
Where can I get the molds?