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Place the tins back in the refrigerator and chill for 7 minutes. Chill for 7 minutes. Chill for an additional 7 minutes.
Remove the chilled muffin tins from the refrigerator and spray it lightly with nonstick cooking spray. Pour 1 tablespoon of the red gelatin into each muffin cup. Top the red layer with 1 tablespoon of the white gelatin. Add 1 tablespoon of blue gelatin on top of the white layer. Top the blue layer with 1 tablespoon of white gelatin, chilling for 7 more minutes. Continue alternating a colored layer with a white layer and chilling the muffin pans until each layer is set. Chill for 2 to 4 hours before serving the shots. Press your index finger gently into the center of a shot. Use your thumb and middle finger to loosen the shot from the muffin tin. Scoop the shot from the muffin tin with an offset spatula. Place the shot on a tray. Continue removing the shots and plate all of them on the tray for serving.