You can make these simple cubes with plain water. To fancy things up, try rose water, orange blossom water, or extracts such as almond, mint, or lemon. Or you can make simple syrup infused with whole spices or herbs. You can even add vanilla bean, edible flowers, or a bit of spice. We made some tasty grenadine ones (yummy in ginger ale), but be warned: They take a full 24 hours or more to dry.
(or more) of water, infused syrup, extract, or a combination
Add 2 teaspoons of liquid to the sugar (and a tiny bit of food coloring, if using) and stir with a fork until well blended. Stir in more liquid, just a few drops at a time, until the texture is like wet sand. It should be almost slushy, but not so wet that the sugar dissolves.
For molded cubes, press sugar firmly into molds and smooth away loose sugar.
To make cubes or use cookie cutter shapes, pour sugar into a straight-sided square or rectangular container and press down to pack it in firmly. It doesn't need to cover the whole bottom — use a dough scraper, spatula, or even an old credit card to press it down and square off the edge.
For cubes, use a sharp knife to cut cubes. Leave them in place for an hour or so, until they're pretty firm, then gently separate them a little bit.
To use cookie cutters, press cookie cutter into sugar, then carefully lift up the cutter and drop the shaped sugar on a piece of parchment paper. If it doesn't slide out easily, use your finger to gently push it down.
Leave the sugar cubes in the mold or on the paper to dry completely. Once they're hard enough to handle, gently remove cubes from the molds and turn them over to finish drying completely. You can put them in a 180 degree oven for 30 to 60 minutes to speed things up. Store cubes in an airtight container.