Arrange your mold or silicone tray on a baking sheet for stability. Measure out 1 cup of boiling water and pour into a mixing bowl.
Add 1 tablespoon of gelatin powder to the boiling water, whisking constantly until fully dissolved and the mixture is clear. Once dissolved, mix in a few drops of food coloring to achieve the desired hue.
3 cups boiling water
Pour the gelatin mixture into the mold, filling it halfway. Place the mold in the refrigerator and chill until the layer is just set, about 2 hours. The surface should be firm and slightly wobbly but not sticky.
Repeat the process with different colors and slightly different flavorings if desired. Disolve the gelatin in boiling water again, add contrasting colors, and pour over the first layer once it’s firm. Chill until fully set, about 2 additional hours, until the gelatin is opaque and firm to the touch.
3 cups boiling water
Once all layers are set, carefully unmold the gelatin by loosening the edges with a flexible spatula or by running warm water around the mold. Observe the vibrant, translucent layers stacked like stained glass.
Slice the gelatin into individual pieces with a sharp knife, revealing the colorful internal patterns. Serve immediately for a bright, jiggly dessert.