Materials for growing large quality sugar crystals
The Exploratorium has directions for making rock candy, the common name for sucrose crystals. In short:


Make a saturated solution of sucrose -- 4 cups sugar dissolved in just 2 cups of boiling water.
Immerse the fabric in the solution, and let it cool slowly (to make larger crystals). You might use a covered styrofoam container to slow the cooling. If crystallization doesn't start in a few days, you might need to drop one seed crystal of sugar into the container.
You can experiment with different types of food color in the sugar solution to color the crystals, but in the process of crystallization, foreign molecules of dye may be excluded from the crystals. The larger the crystal, the less colored it may appear.


Enjoy! Be sure to use sanitary equipment and safe colors, if anyone is to eat this. BTW, ordinary cane sugar is one of the purest substances sold in quantity, better than 99.9% sucrose.