When I was 14 I worked in a bakery. People would come in needing birthday cakes for their loved ones, and if the cake decorator happened to be in she could write “Happy Birthday” on it. But it never actually looked good—the letters were usually off-center and not uniform in size. This idea has been stirring since those days.
Start with a hunk of gum paste (I buy this stuff; making it isn’t hard but is sort of a pain). If you’re coloring the letters with gel color instead of glitter, do that at this point. Smooth it out with a little powdered sugar:
Flatten it to about a 1/4” disk and pass it through a pasta maker to #3 thickness. Or roll it out to about 1/16”. You want it to be thin but not so thin that it will dry out before you have a chance to shape it.
Using a 1/2” square rod (I bought this at an art store, sanded it and treated it with food-safe oil) or a piece of cardboard cut to 1/2”, cut strips out of the gum paste.
Now the fun part! Shape the strips into letters. I use the rods again, this time two wide, as a guide to make them 1” tall. But you can use a nice cutting mat, or draw lines on parchment paper as a guide (make sure to flip the paper over so you’re not exposing the paste to your pencil marks). You could also print out templates for the letters. I just eyeball it.
For letters where you need to connect end to end, like for a “O”, wet both ends just slightly and place the ends together. Then let them dry a little while before pushing them together a little harder. (If you try to do that when the paste is still super soft, you will deform the shape too much.) For letters where you need to attach an end to a flat side, like for a “1”, bend a 1/8” bit at the end, wet that, and press it into the other piece, making sure to turn it around and press both sides.
After the letters have dried a bit, you can more easily press them into the exact right shape. I also like to press flat edges against the rods to make sure they’re super straight. Let them dry totally—overnight preferably—before applying the glitter.
To apply the glitter (this is “Disco Dust” a non-toxic glitter used for food deco), paint the letters lightly with a solution of lemon juice and water. Let that get sticky for a few minutes—it works better when the letters aren’t totally wet, but rather tacky. I paint up to ten at a time so that the ones I started with have time to get sticky. Then paint with the glitter. Let them dry, and you’re done!
Make them crazy big if you want! Your friends are going to be super impressed.