Measure out water, cornstarch, white vinegar, and unflavored gelatin directly into your saucepan. Stir with a whisk or spoon until smooth and no clumps remain. You want a nice, milky, uniform liquid.

Place your saucepan over medium-low heat. Stir constantly for about 3 to 5 minutes. The mixture will start to thicken and become translucent or gel-like. Once it’s thick enough to coat the back of a spoon and has lost its cloudy look, take it off the heat immediately. Do not let it boil vigorously.

Carefully divide the warm (but not boiling hot!) mixture into a few small bowls – one bowl for each color you want to make. Stir your chosen coloring into each bowl. Start with just a tiny bit and add more until you get the shade you like.

Pour thin layers of your colored mixture onto your non-stick surface. You can pour different colors side-by-side, swirl them together gently with a toothpick, or create abstract shapes. While the mixture is still wet, sprinkle on your optional decorations like glitter, small dried flower petals, or tiny bits of tissue paper. Use a toothpick to gently arrange petals or swirl glitter around.

Let your suncatchers dry completely at room temperature. This will take anywhere from 24 to 48 hours, sometimes longer depending on humidity or thickness. After about 12-24 hours, they should be firm enough to carefully peel off your surface and flip over to help the other side dry fully. They will become firm and flexible as they dry.

Once they are completely firm and feel dry to the touch (they'll be hard but still a little pliable), grab your hole punch. Carefully punch a hole near the top edge of each suncatcher. Thread some string or wire through the hole, tie a loop, and they are ready to hang!