Place 1/2 cup of grape juice in a small bowl. Sprinkle the gelatin on top and whisk it in. Allow it to sit for 10 minutes to soften.

Microwave the bowl for 20 seconds to liquefy the gelatin, microwaving in additional 5-second increments if needed until it is fully liquid and clear, but not hot.

Combine the remaining grape juice and ginger ale in a large measuring cup or pitcher. Whisk them together, then gently whisk in the gelatin.

Pour the juice mixture into 16 shot glasses, leaving a margin at the top for the eyeballs.

Refrigerate the shot glasses for about 30 minutes, checking their texture every 10 minutes until it is thick enough to suspend an eyeball.

Press an eyeball into the middle of each shot glass, using a knife or spatula if needed to push it down. Add a second eyeball if desired.

Chill the glasses until the gelatin is completely firm, about 2 hours.