Designing a product for manufacture is completely different from prototype design.
The key is to design the product to have all the components manufactured by machine for ease of assembly and packaging.
The more complicated the manufacturing and assembly, the more expensive the eventual manufacturing price. The retail price of a product is generally four times the manufacturing price, so a small difference in manufacturing price can have significant knock on to retail.
It cannot be overstated how important this is in getting your product to market. Commercial buyers are very price sensitive and a difference of cents/pence can make or break your product.