Since we have been talking about unflavored gelatin, here is a recipe I learned about over 40 years ago when I was visiting a friend in Italy. It makes about 4-6 servings of an appetizer for a hot day.
Get a bottle of fairly decent but not too expensive white wine. You want a less dry wine, possibly even slightly sweet, but you can add sugar if wine is too dry. Pour wine into a sauce pan and add a couple of packages of unflavored gelatin. Warm wine and stir to dissolve gelatin. DO NOT BOIL! You just want it warm enough to dissolve the gelatin. Add a little sugar if the wine is too dry. When it is dissolved, pour wine into a 9 x 9" pan and put it in the refrigerator to chill and solidify.
In the meantime, use a melon ball cutter to make as many small melon balls as you can from a whole melon.
Cut solidified wine into half-inch cubes. Take 4-6 chilled wine glasses and layer a few cubes of wine with a few melon balls. Put filled glasses back in refrigerator until time to eat. Serve as an appetizer.
Instead of wine glasses, you could use short, clear plastic glasses to serve this.