Pour 1/3 cup of cold water into the bowl of an electric mixer and sprinkle the powdered gelatin on top. Let sit for 5 minutes.

Place the sugar and ¼ cup cold water in a small pot and set to medium-high heat. Stir until the sugar has melted.

Attach a candy thermometer to the pot and boil the sugar until it reaches 238F. Brush the sides of the pot with a wet pastry brush if sugar crystals stick to the sides. Remove the pot from the heat and stir until the sugar stops boiling.

Add the hot sugar to the gelatin and stir the mixture by hand whisking for a few minutes to slightly cool. Then beat with an electric mixer on medium-high speed for 8-10 minutes, until soft peaks form. Add the vanilla bean seeds or extract and mix until combined.

Make 1 batch of the marshmallow base. Place the marshmallow base in a piping bag and snip off the end of the bag to make a medium-sized round tip. (All colors we use should be put into a piping bag with the same tip size.)

Line a baking sheet with parchment paper or a silpat baking mat.

Pipe the white tails of the shooting star marshmallows.

Return the mixture to the bowl and dye it yellow. Pipe the middle arch of the rainbow marshmallows, as well as the pot of the pot of gold marshmallows.

Return the marshmallow mixture to the bowl and dye it orange. Pipe the middle orange tail and the star of the shooting star marshmallows. Pipe the gold in the pot of gold marshmallows.

Return the marshmallow mixture to the bowl and dye it red. Pipe the red balloons.

By this point, the marshmallow mixture will be quite thick, so eat the rest and move onto batch 2!

Make a second batch of marshmallows. Dye the marshmallow pale pink.

Pipe the pink heart marshmallows, as well as the tiny arch of the rainbow marshmallows. Return the marshmallow mixture to the bowl and add 1-2 drops of blue food coloring, to make it purple. Pipe the horseshoe marshmallows.

Time to move onto batch 3!

Make a third batch of marshmallows. Dye it pale blue with 1-2 drops of blue food coloring.

Pipe the large arch of the rainbow marshmallows, as well as the blue moons.

Return the marshmallow mixture to the bowl. Add a couple drops of yellow food coloring to create a pale green color. Pipe the leprechaun hat.

Dye the remaining marshmallow dark green by adding some more blue and yellow food coloring. Pipe the clovers onto the hats.

Allow the marshmallows to stiffen at room temperature until they are no longer sticky, but are still soft and squishy.

In a small bowl, combine the confectioner's sugar and cornstarch. Place it in a mesh sieve and dust it over the surface of the marshmallows. Use a butter knife to peel the marshmallows off the parchment paper and flip them over. Dust the underside of the marshmallows in the sugar coating as well.

Place the marshmallows in the mesh sieve and bounce them a couple of times to remove any excess sugar coating.

Store the marshmallows in a sealed plastic container. They are best consumed within 24 hours.