Ingredients are the easiest part of costing your products. You only need to understand a bit about converting kilograms to grams, liters to milliliters and some basic Mathematics, but the Costing Calculator will sort all of that out for you.
Not all ingredients need to be worked out for perfect costing. Other ingredients such as figurines, sugar flowers, edible lace etc need to be worked out on an ad-hoc basis. Example: You will need to have 3 basic prices for your figurines. Large, Medium and Small. The same applies for sugar flowers.
Items such as edible glitter, gel colors, edible pearls and the likes of it, will need to be estimated. Do not think it is unnecessary to calculate. You paid for it, so you need to add the costs. Cake boxes, cake boards, and variety of other packaging can also be put into different categories, but is also fairly straight forward as to how many you use per product you produce.
Rule of thumb is: Always add everything that you have to pay for, no matter how small it is.