To make rock candy at home, first you need a few things. Gather up the items first, string, a stick of some sort, popsicle sticks work good, sugar and water. You want to boil your water. Depending on how much you want to make, its normally three cups. Once it boils, add the same amount of sugar and stir until it dissolves completely. Once dissolved, you will want to pour the liquid into the jar. Wrap and tie the string onto the stick, leaving enough room so a lot of it is in the liquid. Lay the stick across the top of the jar and set it aside to cool. Once it begins to cool and the liquid evaporates, the sugar will stick to the string and form rock candy.