[mmac_]

Often I see someone who will design something in CAD but not think about how the product will be manufactured. Design for manufacturing isn't a buzzword.

It happens with both plastic and other type of enclosures (metal etc). The better designers understand the manufacturing process and build their designs thinking about how they will be created in a production line. As others have mentioned, most manufacturers will say 'yes' to anything you request and charge accordingly. They'll just figure it out somehow, but you'll be unaware that you've doubled the cost of your part due to a lack of understanding of construction.

I guess it happens in other fields as well, i.e. architects vs builders in the construction industry.