With this, you should have a single inventory item as the blank. From there, it depends on if you are creating the customisation before it hits your shelf, or right when the customer is purchasing it.
If you are customizing it yourself before it hits the shelf, then you should create an assembly item for each type of customisation. Then when you customize it, you build the assembly, which takes the ingredient items out of stock and creates one new quantity of the assembly item.
If you are creating the item after the customer pays for it, then you should create group items for each type of customisation. This takes the stock out when the customer pays, but gives them a special price for getting the item and the customisation together.
Thanks!
Peter Eastvold
QuickBooks POS YouTube Channel