In the bowl of a stand mixer or other large bowl, whisk together 1/2 cup of water with the 2 packets of gelatin and set aside. (If you'd like to make boozy Peeps, replace 2 tablespoons of water with 2 tablespoons of liqueur.)
Lightly spray your Peep mold with cooking spray and set it aside. Have a piping bag, rubber spatula, and any additional flavorings like extracts, zest, or powders standing by. Also, place the sanding sugar on a plate and set it aside.
In a medium pot, stir together the remaining 1/4 cup of water, the sugar, the corn syrup, and the salt. If you'd like to infuse your Peeps with herbs, place a sprig in the mixture but don't break it up at all because it will be difficult to remove.
Heat the mixture over medium heat to 240° F. Remove it from the heat, and if you're using herbs, remove them with tongs. Turn the mixer on low and drizzle the sugar mixture in a slow and steady stream down the side of the bowl. Once the entire mixture is in, increase speed to high and let it mix for 10 to 12 minutes, until lukewarm and fluffy. Add an additional flavorings -- 1/4 teaspoon citrus zest, 1 tablespoon matcha green tea powder, or 2 teaspoons vanilla extract -- in the last minute of mixing.
Immediately scrape the mixture into your piping bag and then pipe the mixture into the molds. Let set for 10 minutes. Gently remove them and coat them with sanding sugar.
To give them faces, melt the chocolate chips and then spoon the melted chocolate into a small piping bag or into the corner of a sandwich bag. Snip a tiny bit off the end and pipe on their faces.