How can I create an industrial design for my product?

by experience, you can make developments for existing design, & make the new also

you cannot create it alone,at least you have the idea then the marketing team start to collect the voice of the customer,then it`s translated in to a technical specifications"by engineers", then benchmarking against competitors, trials ,final product design .
this process is known as QFD "to be more specific House OF Quality"