If you blanch the almonds yourself, spread them out to dry well before proceeding. Grind them through the fine blade of a food chopper three or four times until very fine.
Bring sugar and water to a boil in a medium saucepan, stirring until sugar dissolves. Boil hard until syrup registers 240 degrees F on a candy thermometer. Add to almonds and stir until creamy. Sprinkle a large platter with icing sugar. Spread almond mixture on platter, cool, then pack into a large jar with a tight fitting lid. Mixture will be crumbly at this point. Let stand at least one week to mellow.
Gather into a ball and knead on a board sprinkled with icing sugar until smooth and pliable. Knead in a few drops of your chosen flavouring. Makes about 3 1/2 cups.