The word custom-make means to create something according to a specific request or requirement. Its antonyms are generic, ready-made or off-the-shelf. A generic product is produced in large quantities and doesn't have any special feature of specific requirement. It cannot be modified to meet particular needs or preferences. Ready-made items are pre-manufactured to be sold to anyone who wishes to purchase them, it is intended for the general public and can't be customized. Off-the-shelf products are mass-produced, pre-designed goods that are shelf-ready and require no alterations. In essence, these antonyms of custom-make denotes generic, machine-made, pre-designed, and no customizations.