Line 2 baking sheets with parchment and dust with cornstarch and confectioners sugar until the surface is fully covered.

Prepare piping bags by spraying with baking spray and smooshing around the grease, otherwise the marshmallow will get stuck in the bag.

Combine gelatin and half the water in a mixer bowl. Set aside and let the gelatin bloom.

Mix sugar, corn syrup, and the rest of the water in a saucepan. Over medium heat, cook till sugar is dissolved. Turn the heat up and do not stir.

On high heat cook sugar mixture till firm ball stage or till 240 - 250 degrees F. Should form a firm ball when dripped in cold water, but still be able to squeeze it. Not rock hard.

Using whisk attachment on mixer, slowly add in hot sugar mixture and turn mixer to lower speed.

Increase speed to high and mix until marshmallow liquid is cooled down enough to touch. Mixture should be fluffy. Mix time is about 4 - 8 minutes.

Add in vanilla and mix.

Separate marshmallow into 5 bowls and color with pink, blue, yellow, and green. Add raspberry powder into the pink bowl and lemon into the white. You may need to microwave the bowls for 14 seconds to mix in the color if the marshmallow starts to seize up.

Working one color at a time, red first, microwave marshmallow if necessary and pour into a greased piping bag. Snip off a small opening, about a ¼ inch, and begin piping the red part of the rainbow.

Repeat with yellow, then blue. Next prepare the white and pipe the clouds.

If you are doing the shamrocks, pipe 2 skinny loops per each leaf and end with the stem. Or make 3 connected hearts, fill them in and pipe the stem.

Dust the top with the confectioners sugar and cornstarch mixture.

Let sit for 5 hours or overnight. Shake off powder using a large sieve.

Store in an airtight container.