Put sugar, corn syrup, salt, and 3/4 cup water into a pot. Bring to a boil over high heat, stirring to dissolve sugar. Cook, without stirring, until mixture registers 238 F on a candy thermometer, about 9-10 minutes.

In the bowl of an electric mixer add 3/4 cup cold water and gelatin. Let soften 5 minutes.

With mixer on low speed, beat hot syrup into gelatin mixture. Gradually raise speed to high; beat until mixture is stiff (about 10-15 minutes). Beat in vanilla.

Fill shallow pan with powdered sugar.  Fill piping bag with marshmallow and pipe out a large body with a small head in one movement over the powdered sugar.  Sprinkle with colored sugar crystals.  Add eyes with decorating pen.  Set aside, uncovered, until firm, about 3 hours.