Line a rimmed half-sheet pan (13 x 18 inches) with parchment paper and oil the paper.
vegetable oil
In the bowl of an electric mixer, combine the gelatin with 1 cup of water and let it sit.
6 envelopes unflavored gelatin, 2¼ cups water
Combine granulated sugar, corn syrup, 1¼ cups water, and salt in a heavy saucepan. Bring to a boil over high heat and continue to boil until the syrup reaches a temperature of 240°F on a candy thermometer.
2¼ cups water, 4½ cups granulated sugar, 1¾ cups light corn syrup, ½ tsp salt
Using the whisk attachment for the mixer, beat the gelatin at high speed while carefully pouring in the syrup. Continue to beat for 15 minutes. The mixture will be white and fluffy and stiff. Add the vanilla paste and beat until fully incorporated.
1 tbsp vanilla bean paste
Using an oiled spatula, scrape the mixture into the prepared pan and smooth the top. Let sit at room temperature for 10–12 hours.
Lift the marshmallow out of the pan using the parchment paper and cut it into shapes with well-oiled cookie cutters.
Pour the sanding sugars into small plates and dip the marshmallows into the sugar, coating well.
various colors of sanding sugar