Orgeat is surprisingly easy to make. It takes a few hours, but most of that time is just stirring every half hour or so. Here is a recipe from Imbibe - http://imbibemagazine.com/homemade-orgeat-recipe/
Step 1
Place 1 LB of raw diced almonds in a medium-sized mixing bowl. Cover with 3 1/2 cups of tap water and let sit for 30 minutes. Strain, discarding the water.
Step 2
In a food processor or blender, lightly pulse the almonds until they are coarsely ground. (You can also do this with a rolling pin—to reduce mess, put the almonds in a plastic bag first or a pestle & mortar)
Step 3
Return the ground almonds to the bowl, cover with 3 1/2 cups of distilled water and soak for 4 to 5 hours, stirring the mixture well every hour or so. Strain liquid into a 1-liter glass jar through a cheesecloth-lined strainer, pressing to extract as much as possible. Discard the almonds. (cheesecloth is not nesessary, a strainer will do)
Step 4
Add 1/2 cup of cane sugar to the liquid, close the lid tightly and shake the jar vigorously, repeating several times over 15 minutes, or until the sugar is dissolved.
Step 5
Add 1 oz. of white rum and 1/4 tsp. orange blossom water and stir thoroughly. Cover and store in the refrigerator for up to 2 weeks. Makes 2 to 3 cups of syrup.
I added some notes to it. I like this recipe because you don't need to peel the almonds and it is very basic and straight forward. Really tastes better than any store bought as well.
ATP is right, you could also easily make the original recipe. Mess around with some of the flavor combonations and when you get something you like, remember the recipe.
